Here's a bunch of pretty serious little bugs (The first two at least can break or at least mess up the gameplay)
-Grenth's Balance was only halfway implemented. It doesn't check if your life is above the enemy's life (So it will penalize you if yours is higher, the description says it will only have an effect if theirs is higher) and it will happily balance your life points out even if you're at max health (It should only be able to balance 0 if you have max health and they have more life than you) so big boss enemies can take lots of damage very easily.
-Vampiric gaze and touch both have issues if used against an opponent with life regen. This only happens when the opponent is very low on health. Tag them with either of these skills (That should do 52 or 65 damage) and watch them only take 7 damage, be left at a sliver of health, but still live. Since it didn't leech full life, that indicates the victim should be dead. It only happens in a PvP arena (Never seen it in PvE), so I'm suspecting it involves things like mending or healing breeze. Note that they do not gain the remaining 40+ life that they didn't receive as damage, so it's not behaving like reversal of fortune would.
-At the end of a mission, if you have not completed the secondary then both swords end up in the shield. If you have completed the secondary, only the primary's sword is in the shield. Backwards for how it should be.
-In the second to last mission of the game, the secondary either is completely broken, or just requires a very unobvious trick to get it to work (The objective wandered slowly around the map for me until she slowly faded out of sight at a random place, not giving me the secondary)
-In the last mission of the game (And other missions) objectives are crossed out in the wrong order (Completing the second to last objective marks off the last one, leaving the second to last unmarked).