Editing the Coalesced.bin file in multiplayer

It is probably safe:  (I wouldn't touch it.)

http://social.bioware.com/forum/1/topic/343/index/13575450&lf=8

Q: Can I use the invisible weapon glitch? That’s the one that removes the Cobra missile launcher from your back. I don’t get any advantage for using it, but it is a glitch that can easily be done.

A: Since this is a cosmetic change and nothing else go ahead.

I highly recommend posting this question in that thread for final confirmation.  They are rather strict and final with their punishments so if you approach that grey and fuzzy line, and they think you crossed it...