Not completely sure why but using this mod at its latest version (1.1.5) causes off hand items to lose durability whilst mining.

-- Tested on a new Curse Forge profile with only "Geckolib", "Farmer's Delight", and "Crabber's Delight" installed,

Love the mod!

This is now fixed in 1.1.5a. Thanks to everyone for reporting!

Can confirm, had this issue crop up on Craft to Exile 2, localized it to this mod. When going back to 1.1.4a the offhand durability is fine.

Is this to mean, if you have two items held with durability that it will use durability on the other item? And this is not when using the crab claw?

That's correct. If I mine blocks or place blocks with my main hand, the durability of my shield in the off hand will go down.

Been having this problem as well in my own mod pack. Kept wondering where my shields ended up going to.