Some observations, among many unfortunately. Likely to be more I forgot or haven't tested.
General
Bleed on hit / being hit: As discussed it doesn't work, but I have noticed however, while wearing an Enhanced Belt of Bleeding, that it applies sunder at 20% instead according to the tactical camera.
Warrior
'Untouchable Defence' - I agree that it doesn't boost guard by 25%, it does however give my character 20% armor (rear) when guard is up, functioning the same as 'Trust the Steel'. In fact they stack.
'Crippling Blows' - Doesn't apply weakening effect, no noticeable effect at all.
'Grappling Chain' - Sometimes doesn't work on mobs that aren't immune to physical effects (as I'm assuming it should). Also the basic version doesn't do 100% weapon damage as indicated by the UI. 'Give them the boot' upgrade only does 100% weapon damage and not 200% (or 300% if added to base), it applies knockdown and not a stun, which is why it can't prime combos. (intended or bug?)
Mage
'Elegant Defence' - Only reduces the cooldown if the spell was cast upon the caster and it expires, barriers expiring on other party members do not trigger the 4s cooldown reduction. Perhaps intended but the UI description suggests otherwise.