The ultimate Ultimate Adventurer's info thread... :)

Does the Wind Piercing skill really rush bosses? I looked into this and couldn't find any information about it.

I think you're mixing up two skills here.

Wind Piercing = 700% dmg * 3 for UA Archers
Storm Break = 2nd Job knockback skill for Wind Archers

All that Wind Piercing is, is a heavy 700% damage attack (x3 monsters), which is kind of slowish (1080ms). But since it's 700% damage, it has the best potential to knockback bosses that require high knockback damage.