Wax's Earring

I have a question about the hemalurgic spike Harmony gave Wax, the earring. Doesn't the spike give the bearer of it allomantic abilities, like how Spook was able to burn pewter in era 1 because of his spike? Shouldn't Wax have an extra allomantic ability when he's wearing the earring? Or maybe I don't understand the concept of hemalurgy very well. I remember it as someone has to pierce and kill another allomancer through a specific spot to create a hemalurgic spike. Then the next person the spike pierces will have that allomantic ability.