Here is the full list of all 49 Chivalry: Medieval Warfare achievements. It takes around 80-100 hours to unlock all of the achievements on Windows.
Play Chivalry for more than 80 hours
Fire 10,000 arrows with the Shortbow
Successfully block 1000 times
Team up with the Mason Order for 20 hours.
Team up with Agatha Knights for 20 hours.
Survive 10 minutes as King in Stoneshill
Put out the fire beacon in Hillside
Have 20 kills with Oil pot
Have 100 kills with the fists
Play 60 minutes each on Stoneshill, Hillside, Dark Forest and Battlegrounds
Become a Veteran Archer
Gather enough experience with bow weapons
Gather enough experience with crossbows
Gather enough experience with javelin weapons
Gather enough experience with light weapons
Decapitate 2 opponents with 1 swing
Gather enough points to reach level 20
Decapitate an opponent that is on fire.
Gather enough experience with dagger weapons
Become a Veteran Man at Arms
Gather enough experience with one handed axe weapons
Gather enough experience with one handed blunt weapons
Gather enough experience with one handed sharp weapons
Gather enough experience with bastard weapons
Unlock all swords
Become a Veteran Knight
Shoot 40 arrows into the heart
Get 10 Headshots with a ranged weapon in one game.
Gather enough experience with two handed axes weapons
Become a Veteran Vanguard
Gather enough experience with spearing weapons
Gather enough points to reach level 10
Kill 100 Men at Arms.
Gather enough experience with two handed sword weapons
Gather enough experience with polearm weapons
Gather enough points to reach level 5
Gather enough experience with two handed weapons