Well... Khamsin is basically a Metal Gear. Raiden is perfectly capable of suplexing even the largest, like the stadium-sized Metal Gear EXCELSUS. He tore it to shreds and cut through its tougher-than-titanium armor like butter, then two minutes later, Armstrong is beating the ever-loving hell out of him.
The only reason why Khamsin could win is because he can ground-slam faster than Armstrong could harden his nanomachines. However given that he can be very fast with it it's unlikely.
What you did say about the other three winds is pretty accurate, although I don't see Monsoon giving up so easily.