is the dmg of an eth upped zaka higher than a normal upped zaka?

No.

Why would it?

only the def is higher right?

i think because on weapons the dmg is higher if they are eth

A shield is not a weapon though, is it?

Inb4smiteusesshieldasaweapon.

No, this is a common misconception. Eth weapons do have higher damage and eth armor has higher defense. Even though you're using your shield as a weapon, it's still not classified as a "weapon". Thus, if it's eth or not, the smite damage is the same.

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