Tested and confirmed to be piercing damage.
Just went to Wajoam to playwith some lesser colibri.
Higher average dmg/hit and higher average crit dmg/hit than destroyers on lesser colibri, despite being 4 DMG lower.
Sample size about 400-500 attacks on each.
Destroyers- Melee low/average/high: 51/96.55/130
Crit low/average/high: 106/163.82/193
Bird Banes-
Melee low/average/high: 48/109.32/148
Crit low/average/high: 107/187.36/221
Due to the high delay and the piercing not working for ws dmg, destroyers are still better but these have great situational use (Jailer of temp for example) and are amazing for low lv colibri pts for up and coming mnks/pups.
These were wonderful weapons from the time that I could equip them. I did mostly soloing from 50-70, and it seemed that I fought alot of stuff that was weak to piercing weapons. Came in very handy! Good Luck to all you up and coming Monks.
It's true they have a higher DoT and lower WS, however that mean *more* damage for Mnk because our DoT is usually a larger number, Mnk never was known for high spike damage. If we were Sam's it would be the other way around.. As far as I can tell they are almost identical in dps to Destroyers on Greater Colibri. in 300+ fights they have been 1-3 dps higher than Destroyers in my testing.. That shouldn't be.. but guess you have to keep in mind they add a raw 1.25 modifier on every hit. It's a small amount though, so if you like the larger WS numbers just use Destroyers.