How do "earth/fire/etc seeker" and other similar enchants work?

[khadgar]

Do they increase the chances of finding the "fire power" enchant for the right arm slot?

==OR==

Do they increase the odds of every enchant picked up to contain the +fire power modifier?

I want to say it's the latter, but ever since I put on this earth seeker, I'm getting more than expected "earth power" enchants.