This is the reason Numenoreans kept the craft of swordsmithing: it was the most difficult type of metalcraft they knew, and honed the skills of blacksmiths.Don't quality swords take a bit of skill to make? Could Melkor have convinced them to make swords as demonstration of their craft, such that eventually any smith among the Noldor would produce a blade as proof he had attained a certain level of craftsmanship?
Then they could rationalize it to themselves as, "We're not arming for war; we're honing our craft."
This is the reason Numenoreans kept the craft of swordsmithing: it was the most difficult type of metalcraft they knew, and honed the skills of blacksmiths.
But they didn't put the craft aside for millennia, and then suddenly re-invent it.
Also I'm not sure if the Eldar on the Great March were taught to make their own weapons, or were given them by Aule.