Bounty Hunters are members of various village militias that have decided being paid to enforce the law is a better deal than being a bandit (What with it keeping them out of bondage and all.) They've turned in their militia and used their pay and salvage to get themselves a set of equipment greater than any regular militiaman could ever hope to own: A crossbow, saddle or sumpter horse, (usually) a light shield, and/or either a spear, or their militia sword on top of a suit of chain mail. These men form the combination of archer and cavalry base for the Law Enforcer troop tree and can be upgraded into Rangers or Wardens.
They can often be seen in various village militias, being paid by the local lord to track down ne'er-do-wells, or in taverns looking for work, either freelance or through intermediaries who can no longer afford to pay them. More rarely however, they may be after the player when they wander the towns and villages at night, under the orders of a mysterious employer who wants the player dead.
While these men are more than competent enough to face off against common bandits and other low-lifes, up against mid-tier state soldiers they will be utterly demolished due to their competitively poor gear. They do however make great distractions, their ownership of a crossbow prompting cavalry archer behaviour of running around endlessly (and thus keeping the enemy running around in circles trying to catch them,) and disrupting lighter infantry as they charge into them. Dismounted they again show great skill in dealing with the likes of feeble bandits and even state milita units but against the likes of a Ravenstern Footman for example, they'll crumple under the professional soldier's skill and better gear.