So, I guess his armour is supposed to be half way between Ranger and Arnor. The only place I can see this NPC fitting at all is possibly as a melee guard for Dúnedain villages. This is because the Dúnedain didn't really have a strong army after the Angmar wars, so fighting with bows while hidden was really the only effective way of guarding all Eriador. Having a melee unit be able to become invisible would be very unbalanced and wouldn't make sense lore wise, so the only place a Dúnedain would need to fight whilst not being hidden would be in defence of one of their few settlements.

I never said they had to become invisible.

Well Still at anything The Rangers of the North Never really had a melee unit after the Total Collapse of Armor all they had is Rangers

This phrase could be easily misinterpreted... actually not sure what its even supposed to mean, but given you said melee it means we are to find an aspect of the ranger other than their dual-weapon nature or armor status, leaving (to my knowledge) invisibility, and that's about it.

The Dûnedain of the North are just really bland at the moment. I meant to say this unit could be the melee unit of that faction, they won't have invisibility, they won't have bows, they just use melee weapons to fight their enemies. It could have an advantage for the evil factions as well, they won't turn into a porcupine whilst fighting this unit and like that it might become easier to kill some Dûnedain. If there's anything else you want me to clarify, just ask, I'm not that good at explaining my viewpoints.