(i've only tweaked with blunt mastery, hammer crush, and War Frenzy, but have a few questions):
pole mastery, mainly for grind purposes. OE to be able to hit more mobs when AoEing, worth it? and what +++ needed to be really effective? i hope its not like something silly where +3 will allow 1 more mob. or should dorfs just go straight for higher p.atk when using their S.Spears?
sweep/spoil, OE to make earth weak, or go with atk.speed debuff?
can't help you with sweep/spoil stuff but pole mastery for targets increases mob limit by 1 every 3 enchants just like you said while enchanting for pattack adds 1 pattack per enchant
In theory Weaken to earth would work... However the last time I checked weaken to earth spoil.... it only reduces earth element on weapons... and has no effect on the damage you do.