Hey there, that's correct. Glaive Melee only triggers 'on melee kill' perks but also only benefits from melee buff perks also. Weapon damage perks like Rampage, Swashbuckler, etc, only boost damage on the ranged mode. Yes you are technically 'hitting things with the glaive', but it's still just considered to be a melee attack not a weapon attack which is also why it doesn't count as elemental damage, etc.