>>7540746haha to me he looks pretty intimidating.
All bith seem to look pretty similar, but one essential detail for Tenebrous would be 3 folds above the mouth instead of 2 like on the 90s figures. The "eye brows" or the brow ridge should look a bit more angular as well. Another thing that makes him look intimidating is that we can see the red lightning being reflected in his eyes which makes it look like he has red irises with white pupils. It might not be a bad idea to paint the reflection on to the eyes directly. I would probably just try with a glossy black at first though. Seems like the 1997 figure also has the gloss painted on so it will look reflective no matter the lighting conditions.
The armor and paint seem fairly straightforward.
Not sure how tall he should be though.