During the course of Assassin's Creed, there are two types of guards: Soldiers and Archers. The archers are mostly the same, but there are three ranks of soldiers. All guards are armed with swords (with varying styles).
The ordinary soldiers don't wear helmets (Muslims wear turbans) and are only equipped with leather armor or light Lamellar armor. Guard archers are on par with ordinary ones except they are only found on rooftops, wear a hood, and use bows for a ranged attack.
Guard Sergeants (or elite guards) have helmets, the Crusader variant wear chain mail with a tunic, and Mujahideen Sergeants posess medium Lamellar armor.
Guard Captains are the most powerful guard besides the Templar Knight. The Muslim Captains wear Baidah helmets and heavy Lamellar armor where Crusader captains are equipped with chain mail and varying knight helms.
Templar Knights are a special version of guard where only 60 are found in game. They are similar to the Crusader guard captain except with higher stats and the fact that they only wear one version of helmet which appears bloodstained. They will also provoke a fight when they see Altair, no matters what his notoriety level is. Strangely enough, Templar Knights can be found in many places, including Muslim cities.
All Muslim guards speak Arabic, ordinary Crusader soldiers and archers speak English, Crusader Captains and Sergeants speak French or German, and the Templars speak all of the dialects (but only speak Arabic in Altair's fight against Robert's imposter).
The guards in Masyaf, despite being marked as an ally via Eagle Vision, function exactly like normal ones. They are equipped in robes similar to Altair's, but they only have a sword and their skirts are shorter. They have all five fingers, indicating that, though members of the order, they are not assassins themselves, instead serving as guardians.
In Assassin's Creed II, there are five types of enemy guards:
Regular Guards
Those are the "standard" type of guard which can be found almost everywhere on the ground. However, they use a large variety of swords along with maces and war hammers. Those regular troops are
divided into three ranks themselves: Militia, Elite and Leaders.
Thugs are people hired by Vieri de' Pazzi to attack Ezio. While not officially or technically guards, they function in a remarkably similar manner. They will attack Ezio even if he is Incognito, and fight only with fists. After assassinating Uberto Alberti, they can no longer be found in game, except for the Courier mission Casanova.
Militia is the weakest rank. They wear no armor, and can be easily killed (with one counter-kill). They are also the most easily frightened during combat as after battles they are the first ones to retreat.
Elite guards are stronger, wear a moderate amount of armor, and need three counter-kills to be defeated. Elites are also more courageous than Militias although if you kill the leader they still retreat.
Leaders are the best fighters and most tenacious of all the regular soldiers. They wear slightly more armor that their Elite counterpart. The Leaders will last slightly longer than Elites during Ezio's counter-attacks. They also hardly give up their weapons, making them harder to disarm than the others. Also, like Brutes Leader guards can not be grabbed very easily.
The Regular Guards are not especially agile, but can climb up to the rooftops in order to follow Ezio (while not as fast as him). Also, they can recognize Ezio sitting on a bench, but can be assassinated before they recognize him and spread word of his presence.
Seekers
The Seekers, also called "Paranoid" are one of the new special guard types. They are constantly looking in hiding spots (such as the haystacks, benches, and crowds) and checking them (although Ezio can assassinate the seeker from his hiding spot if that happens). They are armed with long spears or halberds, giving them an increased reach in combat. Seekers, like most of the other guards, wear armor. The armor they wear is slightly more than a Leader-ranked Standard, but less than a Brute. When unarmed they will occasionally approach Ezio from behind and then hold him while the other guards assault him. Disarming the Seeker will give you an advantage as you can effectlively use his own weapon against him. They also have a morale rate of 80% which makes them the second braviest fighter before the Brute.
Agiles
One of the new guard archetypes is the Agile, which, as the name suggests, are a very fast, light-armored enemy. They run faster than Ezio and also have the Free Run ability which can lead to chase sequences. They wield small weapons such as daggers and other short blades. Agiles are extremley good at dodging your attacks, one way to kill an Agile is by tiring him out, you can do this by constantly attacking and dodging his moves, however, simply countering an attack performed by the Agile would be solid enough for a kill. Agiles have a morale rate of 40% which makes them the third most cowardice after the militia guard and the archer.
Brutes
The Brutes are heavily armored and equipped (two-handed weapons such as heavy swords and axes). Their armor covers almost every part of their bodies, making them tough to bring down, but also making them cumbersome and slow. They are not very intelligent, and won't be able to tell Ezio from anyone else in a crowd. When deflecting a short weapon, they will not take damage (while all other guards do), but can still be damaged with a short weapon. A good way to make short work of them is to disarm them and counterattack, because they are very easy to disarm. Brutes have two types of attack: one quick, and one that begins with a wind-up. The latter attack cannot be countered, and must be dodged, while the former can be countered. You must possess a Brute's weapon to counter the wind-up attacks of another Brute. Also the Brutes are the only type of enemy that won't flee a battle, they will only run away if you disarm their weapon and if they can't find another one. Your best bet in taking out a Brute is by assassination. When facing multiple guards who are unaware of your presence, killing the brute first is a good idea unless you want to be stuck in a long fight.
Archers
The Archers are guards that patrol and defend the rooftops. They are armed with bows and swords (sometimes maces or war hammers instead of swords), and warn Ezio on sight to leave the place, no matter the notoriety. Approaching them will force them to draw their weapon out and commence a fight. Archers are seemingly just Militia-ranked Standards with the capability of attacking at a distance with their trusty longbows. While Florentine and Tuscan Archers can be killed with a single Throwing Knife, archers in the other cities and regions (such as Venice and Romagna) will need two Throwing Knives to be taken down. Since they are almost always on the rooftops on buildings, Archers are fairly easy to dispatch in melee combat as they have the skill and hardiness of a Militia-ranked standard, making them easy to kill. Another good way to dispatch them is to simply throw them off the roof, which will instantly kill the Archer if they fall more than two stories or if they land in water. The archers also have a morale rate of 30% which makes them a little more braver the average guard.
Coloring
The coloring of the guards uniforms can identify who they serve in the game whether it be a city or a person.
Red caps and sleeves means they serve the Pazzi family (these guards disappear after sequence 5).
Dark red caps and black sleeves with red going down the side means they serve Borgia (these guards usually guard codex pages and appear whenever you encounter Borgia out of Rome).
Dark yellow caps and sleeves with black armor plates means they serve the Medici (they first appear helping you fight the Pazzi during sequence 4).
Green caps and sleeves means they serve the city of Forli (they help you in sequence 12).
Blue caps and sleeves with gold armor plates means they serve the city of Venice (they have much better armor than any guards in Italy).
Black caps, sleeves, and armor plates means they serve Savonarola (they only appear in sequence 13, are as heavily protected as Venetian guards, and can be seen fighting Borgia guards throughout the city).
Pink and orange caps and sleeves means that they serve Rome (they can only be seen in sequence 14 in Rome, they are the most heavily protected guards in the game).
A Quicker Solution
There is a quicker way through Any enemy, but it requires skill. You can easily counter kill any guard with the hidden blades on the first counter, though it also requires good reflexes and timing considering the counter
kill window of the hidden blades is only a fraction of a sword or daggers time window, but if your good at this you should have no problem defeating any type of guard!
The Arquebusiers were firearm-wielding soldiers who served and protected the pontiff during their tenure.
In 1499, armored arquebusiers under the command of Cesare Borgia, son of Pope Alexander VI, participated in the assault on Monteriggioni; one arquebusier managed to wound Ezio Auditore da Firenze during the latter stages of the assault.[1]. In 1503, the arquebusier continued to serve under Cesare, keeping watch over a Papal parade in Rome. At least one arquebusier spotted an approaching Ezio Auditore, but was killed by another assassin before firing his shot.
Papal Guards
The Papal Guard were elite soldiers commanded by the Papacy to serve and protect the pontiff during his tenure. The armor worn by these guards seemed largely ceremonial in design. Although it seemed to serve its purpose well enough, it was unable to stop the blade of the Assassins.
By 1503, the Papal Guard protected Pope Alexander VI, and were commanded by the Pope's son – Cesare Borgia. During that year, several guards were forced to confront several assassins, including Ezio Auditore da Firenze, who had attacked the Papal parade in Rome[1].
Trivia
The Militia Guards resemble the Swiss Guard in appearance because they have similar caps ,swords and similar clothes but different colours.
The amount of counter attacks needed to kill a guard does not affect counter kills with heavy weapons, long weapons or the hidden blade, the guard being countered with these weapons is unable to block or parry.
In Assassin's Creed II the taunts Ezio says to brutes are different then the taunts he says to the other guards, for example one thing he says only to brutes are "Well, you're certainty well fed!"
Strangely, in the mission "Play Along" Ezio assassinates an Agile so he can disguise himself as a guard but instead of having an Agile's outfit he wears the outfit of a Leader guard.
In PlayStation home you can purchase the design of a seeker for your avator, it also comes with a spear for that is the seeker's weapon.
A Brute
An archer.
