Making Unarmed and Melee mechanically distinct?

[Socrates]

Fallout is quite famous for including "unarmed" (which actually includes a lot of weapons that augment punching like brass knuckles and power fists) and "melee" weapon skills. It's no secret the two overlap massively. What can be done to distinguish the two that doesn't require meta knowledge (exclusive perks, unique weapons) or reducing the mechanical variety within them (as making all unarmed faster but weaker and all melee slower but stronger would do)? Guns and Energy Weapons have a similar issue, but the method of distinguishing them is pretty obvious: Energy weapons can have all kinds of whacky secondary effects while gun is pure damage and maybe better suppression fire if that's a mechanic.

Unarmed should just be relabeled to death wish. Good for the meme but mechanically absurd to punch someone to death in full protective gear. If the mechanic must be included it should be clearly stated it's a last resort and using it will likely kill you.