(Ranger) Weapon/Spell Proc

[Feanol]

I've done some testing but haven't come to anything conclusive:

When a spell effect such as Call of Sky allows your character a chance to proc, does this STACK with a held weapon's chance to proc?

Does the same proc per ~1 per min average still apply and both procs are treated as 50/50 to go off?

I've got a Fluxbladed Axe in Mainhand and Call of Sky cast on myself. Does this essentially double my chance of proc-per-round? Are they calculated separately or rely on the same "roll"?

My guess is that you still only get one "roll" per swing to proc, but I don't know how the game chooses between possible procs. Anyone have some enlightenment?