Add a materia that adds slot that can affix specific materia that doesnt break but can be remove how ever you preffer-

T 1 = add 1 slot
T 2 = add 2 slot
T 3 = add 3 slot
T 4 = add 4-5 slot

Slot materia would be 100% affixing Special Materia only that Dt mentioned maybe?
Just to keep the old recycle system-
You can double or tripple meld T4 getting up to 15 slot in materia-
Of course high powerfull materia such as Tripple Cut (FFXII) would use maybe 10 slot
hence you could auto attack x2 tripple cut if You had quad meld T4 materia adding 20 slot on your weapon
--- or you can always use old system and quad meld +20 getting you 80 str instead V_V

On top of that to keep crafting and Endgame Item such as Ifrit weapons-
Ifrit weapons and Endgame Gear should have Affixed slot materia of 10-
meanning you could put a single Tripple cut on ifrit weapon-
While you can try to quad meld slot on reguliar weapon giving you access to add 2 powerfull materia (Tripple cut x2)