By now we all know that grief > botd, for ww barbs, and most other classes who would use a beefy 2h prefer other weapon types. However, I discovered the reason to build a BotD collosus blade! Werewolf form is based primarily on weapon speed, and barbs are fast with 1h weapons, so the common choice is grief phase blade. This reaches 5fpa with ~440 damage. However, the wolfbarb only attacks with the mainhand weapon, so in a duelwield setup the best offhand is a beast simply for the ~200% ED.
Most 2h weapons only reach 7fpa feral rage for the wolfbarb, but barbs attack faster with 2h swords than any other 2h weapons. This means that botdCB reaches 6fpa while a giant thresher is stuck at 7 fpa! Druids attack faster with polearms/staves/axes which is why eTomb Reaver zod/30ias/80ED is best in slot for druid wolves, but a cryptic axe with 90 ias ties with the botdCB at 6fpa for barbs, and has less %ED (360 max vs 415 max).
The perfect ebotdCB has 663 avg damage at 6fpa, equivalent to 553 dmg at 5fpa (to compare with grief PB).
Assuming Lvl 26 might (260%), fort (300%), lvl 24 ww (134%), lvl 24 mastery (134%), 300 str (300%), lvl 8 feral rage (90%) = +1218% ED ~13.18x dmg
440*(13.18+2.00)=6679 dmg for grief
553*13.18=7289 for eBotD CB
eBotD CB has ~9% more dps than grief!
... Ofc I didn't factor in grief 20% deadly strike
too much trouble for me in the evening, with DS from other gear and CS from sword mastery. CB has some bonus ED from +30 attributes and lower dex requirement than PB, and 200% undead ED. Grief has ITD and beast gives %AR. Also has some versatility in allowing for an Azurewrath offhand for fighting undead.
Ok maybe they're close. Still.. A 1.07 base would push ebotd over the top.
Edit: I forgot to factor in sharp charms. A full inventory making room for cube is +108 max dmg or +54 avg dmg.
(440+54)*(13.18+2.00)=7499 dmg for grief
(663+54)*13.18*(5/6)=7875 dmg for eBotD CB, now only 5% more dps.