Well, I just bought GE2RB (no dlc yet cause no wireless), and found out that I could equip higher, unlocked ranked weapons when at lower ranks simply by pressing Triangle on color changeable weapons only, and I could use them in missions!. Example: at Rank 1 missions, you could equip a Rank 11 4Beasts Blade by changing its color (using original color is fine too) whihc automaticallyt equips the blade onto your character. This works for non-dlc GE2RBs currently, I have no idea about DLC downloaded 1.1 + patches and whether they patch this "bypass" or not.
Several, non-lethal glitches may come with this though, as I've experienced two so far, One is that Stats don't change instantly when viewing in Equipment screen (HP,OP,ST), second is that my Assault gun equipped my Blast Gun bullet set all of a sudden. Had to change that back manually.
Why do this? Because when importing GE2 save data thru GE2RB trial ver, the game forced me to start over from GE2's main storyline 1 all over again >< (prolly cause of new RB game mechanics) I got several Rank10+ weps I can use luckily, to hastily advance the already-seen storyline. Too bad that Character Episodes were reset as well.
you people probably already knew all that right? well, I'm just posting to get it off my mind. ^^