The Great Weapon Master feat (PHB, pg. 167) states:
On your turn, when you score a critical hit with a melee weapon or reduce a creature to 0 hit points with one, you can make one melee weapon attack as a bonus action.
The flavour of Great Weapon Master ("You've learned to put the weight of a weapon to your advantage, letting its momentum empower your strikes") suggests that this should apply to heavy weapons (or at least versatile weapons) only.
But as it's written, it appears that any melee weapon can benefit from this. It doesn't appear to specify that it needs to be a heavy weapon or anything (like the other bullet point of this feat, which does).
So someone with a dagger and shield could potentially get this feat and make additional attacks as a bonus action (if they crit or drop someone to 0hp).
Is that right?