you can indeed use an aluminum spike to blank all abilities. I think you would have to hemilergicly charge it, but the given hemalergic ability for aluminum is "removes all powers"
if you want to stick with the connection mechanic (this makes more sense to me) you need to use duralumin. I don't know how you would get that connection back. Perhaps you meet preservation when you figure all this out and he offers a way to 'earn' back your connection to him, or perhaps you find a tiny bead of lurasium that the Elariel's were experimenting with. you would need a reason to eat it... that way "upgrading your powers" would be finding more lurasium, not enough to make you full Mistborn, but enough to alloy with basic metals on increase your abilities in that area.