The comparison I'm making is not the one weapon/two weapon comparison you're rejecting.
The whip was an example to indicate that a statement not explicitly qualified may still be implicitly qualified. In the case of the whip, the statement is "You don't threaten". The implicit qualifier is "with the whip".
In the case of the gauntlet, the statement is "Your unarmed strike deals lethal damage". The implicit qualifier I see is "with the gauntlet".
My unarmed strike is one weapon. When I attack with that weapon, I can use the gauntlet (for example, a punch), or I can not-use the gauntlet (for example, the kick). If I use the gauntlet when I attack with the weapon 'unarmed strike', the unarmed strike deals lethal damage. If I don't use the gauntlet when I attack with the weapon 'unarmed strike', the text of the gauntlet is inapplicable, and the unarmed strike does not deal lethal damage.
-Hyp.