can form wedge

• +10 unit attack
  
• -5 unit defense

This formation arranges the unit into a triangular group designed to penetrate enemy lines. This formation is usually attached to spear and lance-armed cavalry.

can form phalanx

• -4 to being hit by enemy missile attacks
  
• +2 unit morale

This formation causes the unit to lower their pikes. Applying defensive mode off will have the units push their pikes into enemy lines; while applying defensive mode on will have the front line kneel, prevent the unit from pushing forward, and stop any enemy charges into the phalanx's front. Usually used for pikemen.

can form schiltrom

• -1 to being hit by enemy missile attacks
  
• +3 unit morale

This formation arranges the unit into a circular group designed to ward off enemy cavalry charges; usually used for spearmen.

can form shield wall

• +10 unit defense

This formation arranges the men into a dense block with shields at the ready; this formation is typically not used in Medieval 2.

can run amok

Instead of routing, this unit may go berserk and ignore orders, running around the battlefield in a panic.

can form cantabrian circle

This unit can utilize the Cantabrian Circle formation, and receives a +3 buff to its missile attack when doing so.

cannot skirmish

This unit is not allowed to use skirmish mode.

command

This unit inspires nearby units in a 75-meter radius, apply a +4 buff to morale.
It does not buff itself, and this attribute does not stack.

druid

This unit begins chanting, applying effects in a 75 meter-radius; a +6 buff to morale is applied to friendly units, and a -5 debuff to morale is applied to enemy units.
It does not buff itself, and this attribute does not stack

fire by rank

This unit rotates the line forward after the first line fires a volley, with the first moving to the back to reload and the second line moving forward to become the first.

free upkeep unit

This unit can be supported for free in a settlement, as long as a free upkeep slot is available, and the unit can either be recruited or retrained at that settlement.

frightens infantry

This unit frightens all infantry units in a 100-meter radius, applying a -4 debuff to morale.
This stacks upwards to -6 morale with 2 units, and -8 morale at 3 units or more.

frightens cavalry

This unit frightens all cavalry units in a 100-meter radius, applying a -4 debuff to morale.
This stacks upwards to -6 morale with 2 units, and -8 morale at 3 units or more.

general unit

This unit is used as a general's bodyguard.
If assigned to be recruitable in the campaign, a general will be assigned to this unit.
The first unit closest to the top of the EDU with this attribute will be assigned to a valid faction's family member.

gunpowder unit

This unit uses a gunpowder weapon, and receives extra experience from buildings with the gun_bonus modifier.

hardy

This unit has improved stamina, thus depleting it slower, and recovering faster.

hide anywhere

This unit can hide anywhere on the battlefield; if no hide attribute is assigned, this unit cannot hide.

hide forest

This unit can hide in forests; if no hide attribute is assigned, this unit cannot hide. Most units have this by default.

hide forest improved

This unit has improved hiding in forests; this also affects their ability to hide in forests on the campaign map. If no hide attribute is assigned, this unit cannot hide.

hide long grass

This unit can hide in the long grass; if no hide attribute is assigned, this unit cannot hide.

is a peasant

This unit's ability to maintain public order is cut in half

knight

This unit receives extra experience from buildings with the heavy_cavalry_bonus modifier

legionary name

This unit is assigned an extra name based off the region they are recruited from, alongside a roman numeral dependent on how many legionary_name units have already been recruited there.

power charge

Decreases the rate at which a unit's charge stat decays, thus allowing for a more powerful charge attack.

sea faring

This unit is allowed to board ships; most units have this by default.

can deploy stakes

This unit can lay stakes before battle.
Interestingly enough, it is inputted twice, perhaps the second stakes refers to a stake model?

very hardy

This unit has even more improved stamina, thus depleting it much slower, and recovering much faster.

armor-piercing

Pierces armor, halving enemy armor rounded up.

area of effect

Attacks from this weapon affects an entire area

body-piercing

Pierces through enemy units, missiles pass through units and affects multiple targets.

launching

Attacks from this weapon can launch units

light spear

Buffs unit defense against cavalry by +8, but debuffs unit defense against infantry by -4.
If charged by cavalry while unit is bracing, this unit reflects half the cavalry unit's charge modifier.

long pike

This unit's weapon is lengthened. Can only be used for phalanx-capable units.

prec

Unit throws missiles before charging into melee. Fire-at-will is turned off at battle start.

spear

Buffs unit attack against cavalry by +8, but debuffs unit attack against infantry by -4.
If charged by cavalry while unit is bracing, this unit reflects the cavalry unit's full charge modifier.

+x vs cavalry

Unit receives an attack bonus against cavalry units, only even numbers are allowed, upwards to a max of 12.
Requires the spear or light spear attribute to work, and stacks alongside these attributes.

thrown

Unit's missile weapon receives a massive buff against elephant units dependent on elephant unit's hitpoints. The minimum delay to volleys are reduced by 20%. Most throwing units have this by default.