Hello,
Search the forum for "nimcha" and "berber sabre"...granted both are more Morrocan than Algerian, but both would work.
Mamluk is also good, so would other Ottoman swords like the kilij. I have always had the impression that "belly-dancing" is essentially of Ottoman (perhaps as far as Indian) origin as opposed to Arabic.
If your friend self-identifies as specifically Kabyle, then you might reproduce the flyssa (<-- my avatar). We've talked about this type of sword a lot on this forum

and it sometimes occurs in the curved variety. I would personally dislike seeing such a fine weapon used in belly-dancing, but that's just me.
Regards,
Emanuel