Pretty sure Digging Mitts refer to when the enemy's guard is up.Dude my brother blocks all the time! He says its good especially when you upgrade the Digging mitts completely. I myself only use it for bosses .
I still find blocking useful sometimes. When you're stunned (i.e. hit 1-3 times in a row) you can't dodge but you can block. Just hold the block button until it lets you dodge. That's pretty much its only use though, to give you time to dodge which is generally superior. I'd definitely put No Guard on a power weapon, along with No Healing.