You still haven’t given a definition of item that wouldn’t apply to a manufactured weapon.
And it’s not a non-sequitur. It’s the same argument. Abilities that change features to work as other features work as intended.
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A druid may cast spells on her animal companion even if the spells normally do not affect creatures of the companion's type (animal).
Note that it doesn’t say the spell works as if the companion were that creature. Just that you can cast the spell on it. So using your logic, the spell is cast but doesn’t function because the companion is not the right creature type. Because you contend that you can cast masterwork transformation on a monk unarmed strike but it won’t work because the text doesn’t perfectly match your expectations.