I'm doing the quest "A False Front" and i need to "Retrieve the Imperial Courier's Package". After toi ask for the documents, he will become hostile, so stay with your back to a corner inside the Inn and if possible tie a rubber band around your controller so that it keeps the block button (Xbox:LT) pressed all the time. So he will continually strike toi and increase your block skill. toi won't DIE if you're strong enough (my Khajit had block skill 49 when i started this, and after 30 mins he had 58).
Obviously this can be done with any enemy, put this particular guy, named Imperial Courier, won't kill you!!
Also, OH MY GOD my block skill is 61 now and i'm less than one heure doing this!! Also, turn on to the Master difficulty to acelerate the training!! Be careful not to get executed ou anything so turn to Adept when you've Lost a lot of health. Run around the Inn and heal yourself with magic. THANKs. My block is 62 now.