[Animayhem]

I agree light armor feat only feat is someone is going pure arcane. However if somone thinking maybe a cleric/arcane then take the first level cleric as I believe at that level you are proficient in all armors as well a martial weapons. You could go 19/1 Definately still spell. However specialization does work but can be limiting as to what scrolls you can or can not use and mostly if you wish to be a red wizard as they need to be specialized.

If you are going to take two feats and stay arcanist I would say light armor and martial or instead of the armor shield proficiency and martial weapon.
There are many robes out there which can aid in arcane defense plus will spells like stoneskin, shadowshield helps the ac.

This world has tweaked a few spells so my recommendation for first time players here, is to do a generalist Sorce or Wiz to get the feel then recreate.