You asked... "I want the most effective, most practical, most deadly choices. Nothing unnecessarily fancy or expensive."
The short & Sweet answer is, in an extreme crisis - whatever you can get your hand on!
If given time and a choice - Back in my day the good old fashion switch blade was always your best friend in a close quarters fight. You can stash it most anyplace on your person, bring it into action with a push of a button and (please don't mind the pun) get your point across very quickly!
If fact I still have one today, and just like my CCW - I "don't leave home without it."
Does that constitute as a Melee weapon?