Source: Costumes... Whats the Point? Which is Better?
I personally like the Costume Version more than normal version because it evens out the damage more (by changing from “minor to nearby” to the same percentage as the hitter). BUT not only “evens it out” but ends up dealing more net damage when you sum it all up.
If you combine C-Elk with Frigg it will be very effective… Better if you combined with Almur/ Evelyn IMO.
As you identified the Healing Steal is situational BUT it is still highly effective at nullifying a Pocket Healer… Or if there is a Heal Over Time enemy (like say Telluria or Alberich), Elkanen Costume is even more effective as its stealing the heal over multiple turns.