I'm finding many old posts about this feat and many of them answer one or another question about it, but there are also several things that are not as clear. That said this is what I know, or feel I know:
1) MC gives you a +5 in a craft.
2) MC allows you to craft (for this purpose) weapons with magical properties, though your Craft (weaponsmithing) skill.
3) MC states that this allows you to qualify as a caster for other purposes of feats.
4) Those things are a given. From that one would infer that to craft a magical weapon you also need the feat Craft Magical Arms and Armor.
Now let's say we want to make a +1 Menacing Longsword (a +1 ability requiring Phantasmal Killer to create.)
This character would need a scroll of Phantasmal Killer or some other item/ability that would allow him to cast PK.
Question one: Does this mean if he fails he needs a new PK scroll? I assume so.
Question two: Does he need ranks in Use Magic Device to be able to cast this scroll, to enchant this weapon with said ability?
Question three: if you then have skills in Craft (Armorsmithing) can that same character also make magical armors by virtue of the fact he's already practiced at melding magic into his weapon, or does it require a second Master Craftsman feat to get that?
Question four: If he doesn't have ranks in Craft (Armorsmithing) can he use his Craft Magical Arms and Armor, plus some absurd bonus to armorsmithing he achieved from somewhere along the road, plus a lucky die roll to enchant armor without any actual skill ranks that he could not otherwise craft?