My kids are very into pirates and sword fighting right now. Anything long and thin soon becomes a sword so they can have a sword battle. Naturally, I don't like this. Things get knocked down, messes are made and inevitably someone gets smacked with the "sword" and crying ensues.
A few days ago when the swordfighting began again, I spotted our pool noodles (really just one that I cut in half to make 2 - the original was too long for the kids to manage). I had a brainstorm and made a new rule. All swordfighting must take place outside (I don't know why it took so long to come up with THAT rule!) and the only swords to be used were the pool noodles.
It works great! Nothing is knocked over and broken and being hit with a pool noodle doesn't hurt enough to end in tears!
So that's what works for me. Head over to We Are That Family for more WFMW ideas!