No,
melee damage consists of “on-weapon damage” and “off-weapon damage” these names are misleading but what are used
on weapon damage consists of
(weapon base damage )*enhanced_damage_on_weapon+added damage from all sources
Off weapon enhanced damage is
(strength + ed_from_auras + ed_from_skills + ed_from_armor)
Your final damage is your “on weapon damage” multiplied by your “off weapon enhanced damage”
BvC’s (whirly barbs for pvp) have very low off weapon enhanced damage as they have wear enigma and max health, therefore they have minimal strength. WW also has very low extra damage compared to other skills. Even though beast has only ~half the damage of grief, the multiplier from the fanatacism aura is enough that your final damage is higher. You can look up the calc’s online, its in fact more complicated than what i described as they take into account everything (open wounds vs deadly strike for instance) but the main reason is the increased off-weapon ED.
The reason this matters less in pvm is because if you factor in the extra enhanced damage from merc’s might aura and other things the ED from beast is less significant and ultimately 2x griefs does more damage. Take these numbers below with a grain of salt as they are crude guesses but it should help you understand the general idea.
A bvc has ~400% off weapon ED from strength and skills. Lets say each grief hits for 400.
your damage with 2x grief for 1 hit from each hand = (400+400)*(1+400/100)=4k
Beast has about half the damage but adds ~200% off weapon ED.
(400+200)*(1+600/100)=4200
if you used 2x beast it owuld look something like this
(200+200)*(1+800/100)=3600
so grief + beast is the best, beast + beast the worst.
Now imagine you wore a fortitude instead which added 300% off-weapon ED
2x grief becomes (800)*(8)=6400
grief + beast becomes (600)*10=6000
2x grief is now stronger, as you add more ED on (might aura, conc aura from pride, extra strength) grief becomes more and more favorable.
Again the numbers above aren’t actually accurate, and there are more things to account for, but what i wrote above is the main reason why beast is better for low-ED setups (which are the meta for pvp).