For your character concept, you might want to consider dropping item slots into a powerful focus item or two; it'll let you get a solid evocation strength even without being able to spend refinements on specializations.
As an aside, while buying item slots only makes reasonable sense for an ordinary human character, I did run into some issues trying to assemble stats for a low-to-mid ranked fae lord - someone who needed a bit more magical oomph than just the base sponsored magic, but wasn't up in the un-statted "I'm a walking plot point" level of power.
My solution was to allow said noble to buy unseelie magic as a six point power, mimicking full evocation + thaumaturgy, and then buy refinements up from there.