LordCrash, the picture is not very helpful but I can JUST about make out the fact you have a Tenebrium of FOUR.
If your weapon deals Tenebrium damage then 2handed/1handed/bow/crossbow skills become useless and it adds the Tenebrium value instead - since you have a 4 not a 5 in that, it's why you think your damage is off.
I'm having to guess of course, because your picture isn't very helpful but hopefully you'll understand when you check if your weapon does Tenebrium damage if this is the case.
Well, in that case the whole way Tenebrium enchantments work is pointless and counterintuitive imo. Making an ability completely useless after you invested 15 ability points into it and replacing it with a way less effective ability? Wow...
