max block rate?
technically a barbarian needs 280% faster block rate to acheive "max block rate"
and highest possible block rate for a barbarian would be
jewelers monarch of deflection shael shael shael (empty socket)
for 90% (86% breakpoint)

yes shael does make barb get to 42% fbr bp, but it doesn't help as much as edmax edstr or other +damage jewels