I view it much like the self destruct they used now and then on Star Trek. I mean, just imagine the scene with Bob's PC the druid:
DM: Okay, the entire rest of the party is down, the Balrog and his minions surround you. Bob, what do you do?
Bob: I'm pretty much tapped out of spells. Dang, sorry guys, it looks like I'm out of options. I look defiantly at the Balrog and shake my head as I proclaim "I didn't want to do this, but you leave me no choice" as I pull a metal buckler out of my backpack.
Rest of the group: Don't do it, Bob, there has to be another way!
DM: Okay, guys you're all dead or unconscious. No comments from the peanut gallery. The Balrog steps back in fear "You wouldn't dare!"
Bob: "Step away now, or Yanthar's Castle will be remembered as Yanthar's Crater!"
DM: The Balrog, eyes wide in terror "No ... don't do it ... we'll leave right away!"
Bob: giving his best evil grin I reply "Not before you give in to my other demands" with an evil chuckle as the bracer edges ever more closely to his wrist.