Regarding the Heavy Flail build: I do not understand the weapon master progression in a build that has Dev crit. Are you looking for some perk from the weapon master levels? If so I would like to hear your rational.
Mortis the magician - (wiz) - mala Ebekenezer, The Willow Keeper (Druid) - Malbogue Carmen Perussi Vos (Bard x1) - stygia Mutatio (Shifter) - Phleg Redbeard, The Fear Bringer (Str Barb) - cania Em'line Chanter of Ahala (Bard) - Under Construction Sanctus (Monk) - Under Construction Rarg (Fighter) - Under Construction
You need 30 barb pre LLs in order to still receive shapestrong and therefore maintain your 2 extra scripted offhand attacks while using a shield.
You could always do 30 barb, 5 wm, 5 hs for a bit of a damage boost - you'd still get +1 to your multiplier, and overwhelming crit would give a bit of a crit range increase without ki critical, though not as large.