Fortify Block effect helps blocking with swords as well as shield.
"Nearly all Blocking perks work with weapons... the only ones that don't are: Arrow Deflection, Elemental Protection, and Shield Charge. Block Runner works just fine with weapons, and will even supercharge your stealth to make sneaking happen at running speed. As a side note, doing a "shield bash" with a 2H weapon instead does dramatically more damage than properly using a shield, and the Bashing perks work fully as intended with regards to blocking with weapons."
Well, this quote doesn't directly answer your question, but you can infer from this. Or you can just trust me

When your blocking skill is at 100, you get 60% damage reduction without any perks. There are popular builds that use two handed weapon and 40% fortify block enchantment without using up any perks in the block. That brings block to 84% damage reduction. The cap is 85%.
From the Complete Character Design Freedom Thread.
http://www.gamesas.com/topic/1342463-complete-character-design-freedom-damage-resist-caps-and-ridiculous-damage-thread-10/