Just something small and not too huge to add but,
I wish for OOO to add a button that would allow you to switch to the last weapon you have on hand.
As a gunner, I think its a pain to have to press different button if I'm gun swapping with 3 or 4 weapons. Specially if one of them is a back-up sword. Adding this would allow oneself to switch back and forth a lot more easily.
To sum up: Add a keystroke that allow oneself to switch to his last weapon he had on previously.
Put the weapons in the most needed order to the least needed