Pirates

Reborn in a rush to die
Most pirates are undead, and often have no will to live, but rather just want to die in battle, which also makes them immune to all psychological effects. This however doesn't affect any pirates who aren't undead, these people are mostly captains who lead their armies of death-crazed undead buccaneers to raid and plunder ships going between Ymira and Heidrun, on either stolen warships or "tamed" Opelea with decks constructed on their backs, such as the famous Night Train lead by the legendary Captain Mirum.

Classes
Pirates categorize their infantry in 3 different groups, which can be summed up respectively as melee, ranged and kamikaze pilots riding cannonballs.

Buccaneer
The backbone of the undead frontline, these mindless husks of fighters hold their ground against any force, never taking a single step back unless thrown there by their opponent.

Buccaneers use slashing weapons, and have no special skills or traits except for reckless life (see tactics and mechanics below)

Linemen
Opposite the buccaneers, these reborn bowmen have found weapons with more kick, and are putting them to good use, however they often aim up as if it were still a bow in there hands out of sheer habit.

Linemen use ranged gunpowder weapons, they have low accuracy and rarely leave their own ship, unless the frontline needs another hand. They are capable of dropping their weapon and drawing a blade, effectively changing their class to Buccaneer in the middle of a fight.

Cannonball
Unlike the two prior classes, Cannonballs have no sensible reasoning behind their fighting style. These demented skeletons and zombies pack their clothing with steel pellets, only to stuff themselves in a cannon along with a lit powder keg, shooting themselves out while still holding the keg close, essentially becoming the frags of their missile while being able to steer them crowded areas of enemy ships.

Being a kamikaze unit has both advantages and drawbacks, on one hand they have a huge splash area, however they are particularly hard for the Captains to discipline since consequences can't ever reach them after a failed mission, resulting in a quarter of Cannonballs diving straight for the biggest cluster of fighters, be that foe or friend.

Tactics and mechanics
Check Naval battles for warship battle mechanics.

Reckless life
All undead pirates have the trait "Reckless life", making them immune to psychological effects and unable to flee from battle, fighting to the last man standing even against the worst of odds.