The ability states that it gets activated on hit but quite unexpectedly I've seen it activated also on graze attack resolution. To be honest the description of the ability should be reconsidered since it gets activated also on crit attack resolution (this is less unexpected than for the graze, however if we are precise the ability just states hit).

Greetings kmbogd,

 

And thank you for taking the time to notify us regarding the weapon: Beza's Toothed Blade. We'll send this over to our Dev team to investigate.

 

Cheers.