For a 1st pen, you did exceptional. About the only thing that sticks out to me is where the centerband meets the upper barrel. It appears to be slightly overturned. That could have been because of the tenon difficulty. But it still looks really good. One thing that's fun to do with those euros is to replace the centerbands with a complimentary piece of wood. It's a pretty simple segment, and really adds to the overall pen, and eliminates the tenon. Certainly not what I'd suggest for a 1st pen though.
And I agree that a CA finish is the way to go with pens. An even though they will really shine with a CA finish, you can buff them with some 0000 steel wool & give them a satin finish if you prefer.