Well, Sieha, I'm guessing you never had a Sirocco Kukri. The low delay and Wind damage (which is on every hit btw) can make up for the loss of raw white damage.
This coupled with Mandau will make just as nice a combo as Mandau/Sirocco did before the level cap was raised.
Sieha the reason this is so great as an off-hand is because it let's you Rudra's faster without a massive hit to DPS, it out-does the previous best of augmented Atoyac.
all the weapons from unity ive seen have had not very good dmg vs say alluv skirmish weapons but not by huge amounts. this weapons looks like it would excell as the Aloeoan edge WS for like amber spamming in abyssea