Well Regendorf
There was nothing here has been no indication that 1h-straight sword is required to unlock 1h-curved sword.
And in-fact, 1h-curved unlocks Katana skills but only after doing something special (which I am not sure of, but appears to be equipping a special katana first)
We have neglected to do that, since people wanted katanas, so we have gotten rid of this particular extra skill. We may introduce others later, if we see it fit, but most weapons are allowed. 

On that note, claws are a legitimate weapon in SAO, and are definitely available early on, although, I do not know if they were unlocked or were allowed from the start. For this we will probably allow it from the start, regardless. The player in SAO, Argo, which has very little time in both the light novel and anime, but has more on in the Progressive series, is a player who utilises claws, and uses them at least from the second floor. So yeah. Go ahead and use claws.

Edit: Hm... unsure about the dual usage of claws. I don't have details whether she used two or not. In fact, there are no details. And it would contradict the theme of only one person having the unique skill [b]<<Dual wield>>[/b] unless the two claws count as one set equipment, therefore, one weapon, hence, not dual wielding.