It looks like the guards in phase 2 can be disarmed:
From wowwiki http://www.wowwiki.com/Onyxia_%28tactics%29:
Note that these guards can be disarmed, which prevents them from being able to damage anyone with Ignite Weapon, also the Ignite Weapon buff can be dispelled/purged.
I think the only changes we need to make to get her down is on phase 3 when she lands, the main tank
needs to make sure to avoid the initial fear so he can move her to the phase 1 position while
all the adds are taken down.
Also, in phase 1, the main tank should be the only person taking damage so lovely should help kirana heal to save
mana.