Here is the full list of all 14 Weapon of Choice achievements.
Collect all MBG pies.
Beat level 1 (Mountain Village) in under 1 minute and 10 seconds.
Beat all branches in MEGA-WICKED difficulty.
Beat a game branch without activating death-brushing.
Kill 10 enemies with the SPIKE LIFT.
Beat a game branch only killing bosses.
Use Xerxes to reach a boss without touching the ground.
Beat all branches.
Beat the Evil Sun.
Use the SMOKE WALK for the maximum time.
Rescue every Solus Operative.
Kill 10 aliens while hanging by the SPIDER PACK.
Shoot 5 birds.
Rescue someone and get them out of the level.