I think even if it was an appearance it would be cool, or maybe you could stat it but damage would not be increased. It would further customize someone's character look, or dual wield would be one item that is similar damage to what is available so it's not an OP item causing everyone to want it.
The implementation of dual wielding is easy and we have done this in tests already, the animations however are horrendous.
For duel wielding pistols there are some existing stances I played around with that are workable because there aren't on ton of extra animations involved with holding pistols. Holding two handed melee, you are constantly doing weird things or stabbing yourself with the second weapon because no good animations exist.
For a modern engine line Unreal that uses common animations, this is easy, for SWG, I've found no open source tool that will convert normal animations to SWG's proprietary file type. If any server projects have such a tool, they aren't sharing.