Okay so I wasn't really missing something to consider that would make runemaster a great pick. That's a shame.

I currently have a runemaster, but was looking at character planner of a Thane and noticed a Thanes spells delve higher than all but darkness spec nuke, have longer range, lower cast time and less power. Thanes also have their full chain, can spec high into shield for block and 9sec stun etc. Can so...