Is the stun threshold on Mortem Morsu a local or global mod?

If you were dual wielding a regular weapon and Mortem Morsu, would the stun threshold reduction apply to attacks done with the main hand weapon?

If so, is that still the case even if the attack you are using isn't compatible with claws? For example if I had a sword in the main-hand and the claw in the off-hand, and I was using Cleave... would my cleave have the stun threshold reduction from Mortem Morsu?