В процессе Can the Claw of Beliar be upgraded besides the shrine?

[corrupter]

I got the claw of beliar, the base dmg was 190 and bonus 30.
I've upgraded it after talking with Rhen and the Seer in the Beliar's shrine, now it's 240 and 40

Would love to know how much is the extra dmg for it? (40% chance to do extra dmg, but how much is it?)

Also I didn't manage to sharpen, poison, harden it. Is there a way or it doesn't work for it?

 

[n1kx]

The claw must not be sharpened or poisoned.

Additional damage as in the original - 100 damage when the effect is triggered.