If you really want to know you can look through a list of the Dragon Knight Saga Achievements
. There is one for the killer bunny and the white chicken, so that could account for the two you don't have.
Thanks! Fortunately I found the other one quite quickly: "You sided with Behrlihn." Which I didn't, and don't intend to, so I guess that'll remain locked! I dealt with the white chicken on a previous play-through as I didn't want to leave the quest unresolved, but it didn't feel quite right... I left it alone this time, alongside the chap with two personalities.