My suggestion would be drop focus for spellweave first. Unless you have difficulty getting a level 6 focus.
Otherwise, necro is a great option. Wraith form is great, this spell alone is incredibly powerful, and you get a bunch of other cool spells too.
You can keep inscrption also, soulstone resist and focus. Make sure you keep them around though. You will want both at a later time. If you mainly are PVM now, and you plan to spawn, you are most certainly right; you will pvp.
Happy hunting.