Here is the full list of all 26 Braveland Pirate achievements. It takes around 15-20 hours to unlock all of the achievements on Windows.
Game completed using only the hard level of difficulty.
Rejected all the assassination contracts.
Have won 150 battles.
The Great Reaper defeated.
Game completed without using the easy level of difficulty.
All the bosses defeated.
Looted all treasure chests and hidden caches.
Obtained the old man's artefact in the sea.
Visited all islands.
All pirate tricks learned.
Have answered all the questions of the sages.
Fulfilled all the assassination contracts.
Jarl Erik defeated.
Have overcome 25 random encounters in the sea.
Rejected the Iron Bank's offer.
Fought through all dungeons and arenas.
Page on Facebook or Twitter visited.
Sir Rodrick defeated.
Six pirate tricks learned.
All four equipment items on.
Bought an item for hero.
Davy Jones defeated.
Looted 7 treasure chests and hidden caches.
Pirate trick learned.
You defeated the army without losing a single warrior.
Cabin boys have joined you.