My friend Spencer Reiter (SAR Knives/SAR Global Tools) sent me a couple of his Titanium Combs to play with. These are functional combs for those of you with hair, but they're also excellent adaptive defensive tools.
The two that arrived are his 'Hornet' comb, & his Ringed comb. The grip on the Hornet comb is based on the grip & hilt of his Hornet knife. The Hornet comb is very effective in a front grip, with the 'tail'on it causing an immense amount of pain with very little effort. When applied with a pinch grip it causes an great deal of pain as its dug into flesh. What most folks won't appreciate without seeing is just how effective this would be using the teeth to rip against bare flesh. I started playing with them against a tough cardboard box, & they ripped through it like it wasn't there! I'd hazard a guess that they'd be VERY effective against hands & face!
The Ringed comb is particularly comfortable in a reverse grip, & the tail on the ring is very effective as a thrusting device, & the teeth can be used for 'cover & slash' type movements.
The combs come with kydex sheaths, & I really can't recommend them enough. If you're concerned about your personal safety, but live in a 'non permissive environment' they'd be right up you alley. Spencer can be contacted via his blog http://sarglobaltool.blogspot.com