You have a new passive skill called 'seething fervor'. It cannot be trained,
but is learned by doing. You learn it while your fervor is on. Check 'fervor
status' [same as what I called anger in previous post] to see its level.
And, you might have noticed already that Burgle crits have a chance to drain
the vitality from your target -- in short, you gain when they lose. This
special effect drains more than just health.
It will also take a bit more for first anger message to appear so that tiger
claw etc irrelevant spells don't immediately spam without any noticeable
effect.