Just like Druidstaff’s list back in RMCI, they never posted whether it was NM or M.
We always used Magic, though I would ask that the player adventure for finding the magical wood needed to craft such a staff, so the wood itself was actually magical and thus allowed Magic boni.
Do the same with the blade. Have the PC quest for Magic Low Iron(a meteor lands somewhere and he has a vision or sees it happen).
After that, let the spells do the rest and shape it.
This helps make the blade special vs, “oh, I can make these a dime a dozen.” (even though only one at a time is a ruling for the fine print of the spell)
If made with regular metal, it will have a NM bonus, instead.