Here is the full list of all 20 Crossbow Warrior - there are The Legend of William Tell achievements.
Shoot the apple off your sons head.
Jump off Gessler's boat.
Beat the big Habsburger.
Survive the showdown.
Reach the Alps.
Play your first sniper level.
Collect 200 Edelweiss.
Collect 30 pieces of cheese.
Collect 30 pieces of chocolate.
Get every Edelweiss, Apple and best time.
Shoot 50 bolts.
Jump on the head of 3 Habsburger's in a row.
Kill 50 enemy's.
Drop a crate on a enemy.
Get best times in half of the levels.
Beat the last level with only three bolts.
Use the rail cart to reach the apple.
Don't shoot your crossbow in the last level.
Miss the apple and shoot your son.
Nearly finish the Nordwand level, but fall all the way down anyway.