Magic Staff included in a weapon

[Xefas]

Would it be possible to circumvent the 50% cost increase for combining two magic items to, first, create the Staff of Power as normal and then, separately, create a magical barbed dagger - then Sovereign Glue the dagger onto the end of the Staff of Power? That works out to be a polearm, more or less, right?

I know 3.stuff edition is usually on the side of punishing creativity, but that sounds like it would work.