To be completely honest, I use to say all the time that it's possible that Rayleigh did train Luffy in the basics on how to use a sword. I mean he spent almost two years with a Master Swordsman, and it's not like Luffy has zero weapons experience, because he did wield a pipe when he was younger. He just always chose not to use one. But one thing I've noticed, is that with the enemies now, they are all using weapons. So Oda giving Luffy a weapon, whether it be a sword or a staff, or even both, is not out of the realm of possibilities.