I don't believe any link has ever been shown between magical WS acc/dmg and the weapon's combat skill. So there's no reason why you couldn't do that DMG with low skill. Might be hard on post adoulin mobs though, due to the non ilvl weapon's lack of M.ACC skill+.
There is an main hand ilvl modification on magic ws now, so you'll be very limited when using weapon types that SCH can't wear Ilvl versions of.
Tenzen WS neck? The neck tenzen drops would be this.
Mizukage-no-Kubikazari. I suppose that's usable for a magical ws. But I'd think you'd be better off with an Eddy necklace
Did you mean this?
Sukeroku hachimaki. It's a head piece though. Not that it's all that good for magical WS either. I don't think WS accuracy counts as magic acc.... But then I couldn't say for certain, I doubt it's ever been tested.
I did see that you said for fun, but if one wanted good magic WS dmg on SCH wouldn't it be simpler to just use Omniscience? (or Cataclysm? You'd have to sub one of the job that gets it natively, but you're already having to /drk for sword WS.) It's also on SCH's best weapon type. And Staves tend to have high magic dmg+ and high M.ACC skill+. Should make for some very potent WS.