So instead of Oathing in into 6 power flying trampling hasters, you want to Oath into shit like Witness and Negator??? I think you need to learn the basic concepts of the Oath archetype. The point of Oath is to win in 2 turns after you play it. Negator doesn't do that-he's not big compared to Akroma or SotN. DSC gets Welded out. Witness is just terrible.
Eternal Witness: after filling up your graveyard, why not grab something that might be handy from there? I like recurring Time Walks, how about you?
After filling your graveyard, why not just Oath into a guy that wins you the game?
Akroma/Spirit is overrated, I used them when I originally started with Oath and wasn't very impressed.
It's so overrated that the Oath decks that made top 8 in Richmond and Gencon used them.
Also, you have no draw engine (Brainstorm doesn't count). Deep Analysis doesn't count because you need your draw engine to find your Oath. It is only good after you activate Oath. Meandeck Oath used Intuition/AK as a draw engine, GWS Oath uses TFK and Impulse. Other builds use Skeletal Scrying. You need a draw engine. Cut 6 creatures for a draw engine.