Would be cool that if you took your primal weapon from a lower (easier primal) and either fought a higher difficulty or higher tier primal you could unlock an upgraded version of that weapon.

So Ifrit wep -> fight Ifrit hard(er) mode -> get a upgraded Ifrit weapon.
or take Ifrit weapon, go kill higher tier primal (like Garuda) get upgraded Ifrit weapon.

I would like to see primal weapons be similar in power (when they are similar in difficulty to acquire).