I've got a Selonian PC wanting to make two-weapon attacks with his two-handed vibroaxe and his tail. I'm okay with this. What do you GMs think?

The increased difficulty that you get from the different skills (Melee and Brawl) seems balanced to me.

Seems fine. No idea why they'd want a 4 difficulty starting combat check though.

I would allow it too. Their species gives them a distinct advantage that makes it possible.

On a related note, I'm playing a Selonian Jedi on a PbP, and I keep wishing I could add attachments to the tail. I can't get rid of the idea of using paired weapons on tail and saber.

Using cybernetics I'm sure a case could be made for grafting on a weighted head. Wouldn't go for a balanced hilt though...too much surgery in the wrong place...

Don't forget that the tail uses Agility rather than Brawn, so if both are not equal, the dice pool might be even less attractive.