If somebody kills the enemy that you're preforming a finisher on, the Karnstein Armlets Restoration and Cure doesn't activate. This can make using Karnsteins outside of solo play incredibly frustrating. Having the buff activate on finisher instead of on finisher kill, similar to how Proximity Ward activates, could fix this issue. Alternatively, fixing the ability to kill enemies getting finished would be better (which is a bug in and of itself), but if I had to guess, that may be easier said than done.