How does Critical Imbuing work on the Soul Set items?

Question

With update 2020 we received few new items with extra attributes on the weapons- like Critical Hit chance 10% & critical extra damage +10% (example: You see a souleater (Atk:10 physical + 47 ice, Def:34, axe fighting +5, critical hit chance 10%, critical extra damage +10%).

Imbuements: (Empty Slot, Empty Slot, Empty Slot).

It can only be wielded properly by knights of level 400 or higher.

It weighs 72.00 oz.), which can still be imbued with Critical Hit. How does it work and how is exactly calculated?

Question based on overheard information that it does give 60% Critical Extra Damage, however Critical hit chance remains 10%. 

Answer 1

Question based on overheard information that it does give 60% Critical Extra Damage, however Critical hit chance remains 10%. 

This is correct. When these weapons are imbued with Powerful Strike you'll get 50% + 10% Extra Damage and 10% Hit Chance. The "secret" here is to pay attention to the weapon's attribute description: it says "critical hit chance 10%" and "critical extra damage +10%", note that only the damage has a leading "+" sign. 

This permanent 10% hit chance is only there so the weapon has a chance even without the imbuement.