since the armor spells and dragonhide both svck.
Come again?
I'm rolling a spellsword and I LIVED in armor spells for a LONG time.
Only recently swapped to light armor after maxing enchanting (Was using archmage robes up until now. Had 1 perk in Mage-Armor... which I also used when I've been forced to give up my gear... for... uhm... some reason

)
I still use armor spells to give myself a fat bonus to my armor for any harder fight (if I'm takin on a Giant... and not going to just stun lock it

... then I want that armor. Boss fights, Snow bears... etc)
Dragon hide + ebonyskin will make you practically impervious to melee damage for 30 seconds.
Paralyze (expert level) is a great off-hand attack and mass-paralyze is additionally ridiculously powerful.
Conjuration Master spells are obviously worth while.... and are out of combat casts so who cares about mana cost and cast-time
I could see Restoration master spells being more useful if you had more followers... as-is doubt I'll ever cast it
Anyways... Destro magic could use some scaling... but dual-cast expert spells deal around 200 per cast fully buffed with perks (only 2 per element) and stagger enemies. (60 base dmg. +50% dmg from 2x perk raises single cast damage to 90. Dual-Cast is slightly more than 2x damage which is 180+ some change and of course Impact)
Additionally, you can craft potions that will further pump destro magic for a short time for any boss fights where you really need to crank out the damage.
Combine with either Free or insanely reduced magicka cost from gear and you've got a character who can hit pretty hard, at range, quickly, while stun locking enemies, indefinitely.
Also, when cost is free from gear (or reduced in cost 75% off from gear on half base cost with perks leaving only 12% original cost) the mana cost on master spells really ain't that bad.