The main hand 'Bare Fist' weapon is properly replaced by 'Grudge Claws', but the subhand 'Bare Fist' weapon remains. This means you can't use grudge claws with mixed martial-arts, and acts a little oddly if your main hand is empty to start with.
Further notes about Grudge Claws:
- The on-hit Dark damage is calculated using your unscaled Will, like back in pre-GR, not anything like Dark Attack.
- Most autohit skills use Grudge Claws when calculating damage (i.e., Light Tomahawk), but certain abilities (Geldoren is the only one I found, but I didn't have access to testing all of them) will use Bare Fists instead of Grudge Claws, despite the player-debug information prefacing the attack with Grudge Claws' power/stats.
- As mentioned above, attacks with the off-hand never use Grudge Claws, and only use Bare Fists. This is true when attacking with Sub-Attack granted from Mixed Martial Arts, or when attacking with your off-hand because of Twin Dance.
This should be corrected.