Mercenary

A Mercenary is a class of soldiers that use swords only. They tend toward balanced statistics, although they generally have low resistance. Their defence is usually higher than a Myrmidon, but they may not be as fast. They have very high skill stats and decent strength, along with better HP than the Myrmidon. Their Luck does suffer sometimes, though.

Combat
Mercenaries are some of the most powerful fighters you can have on the field since in most cases they can deal lots of damage while being able to take a few hits as well. Their one problem is that once they are surrounded by enemies, they can't leave the battlefield since their Movement is mediocre. However, a high-level Mercenary can dispatch hordes of axe users with ease, and even stand a chance of avoiding lance and sword attacks. They will more often than not strike their target, and score a few Critical Hits due to their high Skill.

Promotion

 * Hero, usually with a Hero Crest.
 * Ranger or Hero using the Hero Crest in Fire Emblem: The Sacred Stones
 * Myrmidon, at level 7 and after visiting a shrine, in Fire Emblem Gaiden

Notable Mercenaries

 * Ogma - Fire Emblem: Ankoku Ryū to Hikari no Tsurugi
 * Nabarl - Fire Emblem: Ankoku Ryū to Hikari no Tsurugi
 * Radd - Fire Emblem: Ankoku Ryū to Hikari no Tsurugi
 * Caeser - Fire Emblem: Ankoku Ryū to Hikari no Tsurugi
 * Dieck - Fire Emblem: Fūin no Tsurugi
 * Oujay - Fire Emblem: Fūin no Tsurugi
 * Raven - Fire Emblem: Rekka no Ken
 * Gerik - Fire Emblem: The Sacred Stones

Also See

 * Myrmidon
 * Ranger
 * Hero

Trivia
It is possible that the mercenary's Critical Hit animation from Fuin no Tsurugi, Rekka no Ken and Sacred Stones was the inspiration for Ike's Aether technique. It is also possible that in Radiant Dawn, Ike classed up from a Mercenary to a Hero.