Destruction Mage and robes only

[JechtFayth]

I will have to test to be sure (not home right now) but doing maths I have reached to:
For example a resist frost enchanting would normally cap at 47% using a fortify enchanting potion it would make the frost resistance cap at 59%
so there is the difference. Pretty huge in my opinion.

for enchanting robes and such, does that go into the category of magical armor for the arcane blacksmith? or do you not need that.... all i want are robes and being able to put enchantments on... just saw the arcane blacksmith and was wondering if that is also needed for robes...