When you play as a giant monk, Master Kaen should also be a giant, complete with giant-sized robe, so when you defeat him you can get a usable robe as well as the quest artifact.

Master Kaen should be able to smash boulders in his way, so that the player can’t easily defeat him with a boulder fort.

King Arthur gets the same resistance suite that the player gets for crowning, and the Grand Master and Master Kaen get the suite of intrinsics that high-level monks get.