I understand that too much of an increase would tip the scales back in favor of MT DRK, but it's an alternate route to better "physical" mitigation by giving more reactive HP regen as opposed to proactive reductions.
And I remember the Thordan's as well, I ended up clenching often because one or more healer's are dead.
It's not that Soul Eater is a PROBLEM per say, it's just the most obvious tool for further mitigation being added too it, given it won't change Dark Knight's rotations (we already use it for basically every occasion) and that it'll just be making a good thing better.
It's really about adding mitigation without changing skills majorly. More healing on SE would just mean Drk has better recovery options from big hits (compared to Clemency (when well timed) and IB/Equili) than it currently does.
Other options would be adding a small defensive bonus to Dark Arts (5% physical for 10 seconds). I don't want to see Dark Dance getting any more defensive skills (because CD would have to go up) and I cannot think of anywhere else on the current kit it could go.
