SSS-Druid said:
Rock. These are simply amazing. 
Gambit: Gambits ability to imbue items with kinetic energy has a lot to do with the strength of the item. Something that is very lightweight and easily destroyed (like cards) doesn't do as much damage as something made of tougher material, but it is faster to imbue. That's why he uses cards instead of knives - cards can be "charged" to their full kinetic potential in the blink of an eye, but a rock or dagger would take longer to fully charge, and the items only detonate if they are fully charged. My suggestion would be some kind of weakness to the power, that limits how many extra d6 of damage it can do based on its hardness. IE - Hardness 1 and under is limited to +1d6; Hardness 2-5 is limited to +2d6, etc.
Also, when he first appeared, Gambit possessed some very minor mind/emotion control powers that he used with some skill. This was in the days when Nanny & Orphanmaker had reduced Storm to a child, and the rest of the X-Men thought she was dead. He used this ability against Nanny, but she threw it off. I'd suggest some kind of basic ability that grants hefty bonuses to Bluff/Diplomacy rolls, but can be resisted with a Will save.
Just some ideas. They look awesome!
Actually I think that emotion/mental control was better than you give it credit for. It swayed a shadow king puppet for example. Also when he 1st showed up the shadow king had tracked down storm with his pwoers, gambit shows up completely not sensed by the shadow king makes a quick escape with storm and neither of them could be detected by the shadow king while he was actively searching for them. (a few other hints here and there)
Flash forward a few comics their in space a Xavier cloneish thing who tapps all of Xaviers powers+psylocks i think+the imperial guard mentailist chica powers couldn't get a hold of gambits mind, and everyone in the x-team can't penetrate his mental defenses.(couple hints for a bit than they dry up)
Flash forward some more comics(couple years) gambit in a coma, psylocke says hey his defenses are down now elts peak in and see what makes him tick. Gambit notices and kicks the crap out of her psychic form in mental combat.
Flash forward some more one of the many X-men reorgs. Jean Grey chilling, starts going to her own memories into the part of her mind most protected. What does she find, a palying card implanted into her past memories. Gambit sent a message meet me in Russia.
I haven't read the X-men in about 9 months so I can't say if other hints were dropped. But at the very least give him a solid mental D. Will save+7 looks pathetic to what he displays.
Also don't know if this ever translated over to the main books but in the short lived gambit comics he learned how to time delay the explosions.