I found a glitch on the PS3 that involved me trading items with my companion (Charon) and I duplicated a Super Sledge just by giving it to him and playing the game for a while. I looked in his inv and had 2 Super Sledges equipped (yes he was wielding 2 super sledges at the same time although appeared as only holding one) one was at about 45% health and the other (the duplicate) was 100%. I'm not as sure as how I accomplished this but I found it quite amusing.
So if you want to test out finding glitches keep that in mind.
Also note that he was holding the sledge one handed instead of normally, Not sure if that correlates with the duplication but its safe to state it.