First, a Samurai sword may be a tool, but it cannot replace a screwdriver, file, or anything that comes out a Craftsman toolbox. You're more than likely going to do one of three things.
1. Break/damage your airsoft gun OR your sword.
2. Break/damage your airsoft gun AND damage/break your sword.
3. Break/damage your airsoft gun AND hurt yourself.
Any way you slice it, bad things will happen. Creative thinking of this kind isn't worth a trip to the emergency room. Best bet, pick up a cheap tool set. Another thing to remember in future, measure twice, cut once. It will save you future headaches. Another thing you need in your toolkit is patience. When you get frustrated, you don't think, you act. When that happens, all bets are off. Odds are you're going to be mad because you broke something or you hurt yourself. When all else fails, ask for help. Help isn't a dirty word. **** is a dirty word. That's what you'd be screaming if you missed with your Katana and wedged the blade into your femur or foot.
Swords, like guns, aren't toys. Unless they're plastic and painted funky colors. Same thing applies to the steak knife and even the butter knife too. They're for eating and cutting meat/bread/cheese, not dealing with a phillips head. I'm not saying this to get on your case, but any number of these things that you used to jerry-rig a fix, could either send you to a hospital or end up leaving a blood trail on your parents white living room carpet.
When something gets stuck, take your time. The more force you apply means the odds of an accident go up. Plastic shears and snaps in fun ways. Something gets stuck, take a breath and see where. Then go backwards from there. Examine the problem and think of ways around it rather than applying brute force. Brute force ends up breaking things and wasting money. Wow...where the hell did that rant come from?...
Back to the question, I'm with Angel. Magpul AFG or RVG. Both are easy to install, shouldn't get stuck and are very comfortable to use. Another option would be handstops. EHobbyAsia, LaRue, and Magpul offer these alternatives to foregrips. http://store.magpul.com/product/MAG414/46
- Magpul AFGhttp://store.magpul.com/product/MAG412/46
- Magpul RVGhttp://store.magpul.com/product/MAG511/46
- Magpul XTM Hand Stop Kithttp://www.laruetactical.com/larue-tactical-handstop-2-piece-set
- LaRue Handstophttp://shop.ehobbyasia.com/t-s-c-cnc-gear-sector-rail-mount-hand-stop-titanium-green.htm
l - Gear Sector Hand Stop