Neptune has Guandao and Trident form. Pyrrha has a spear that transforms into a sword. Sun has a staff that becomes nunchucks.
So yeah, we've had plenty of examples.
Neptune's weapon has two gun forms in addition to the Guandao and Trident forms. That's actually a javelin which is used for ranged attacks not speaking of the fact that Pyrrha's weapon also turns into a shotgun. Sun's nunchucks double as guns.
Those weapons that do have more than one melee form aren't all that different, sword and javelin, staff and nunchucks, Guandao and Trident are easily alterable into one another (at least by RWBY standards). We haven't seen a weapon that transforms that completely from one class of weapon into another unless it is becoming a ranged weapon.
Yes I realize I said I didn't think we'd seen a weapon with two melee forms. I misspoke, I meant a weapon with multiply melee forms that lacked a ranged application, that's my bad.
That said I'm not disputing that the guy in the photo is Qrow (I looked him up). I don't think the weapon he is using however is the scythe that he will later teach Ruby to wield, which leaves me wondering why he'd change his arsenal so completely like that.
