Analyzing the trophy descriptions...
It seems Arc's route will only have one ending, since there's one single trophy for "get Arcueid's ending", meanwhile Ciel has one for "get Ciel's TRUE ending". There's a generic "get one ending" trophy but it's named after Ciel's route.
Getting some mixed signals here. There's no trophy for "get Ciel's Normal/Good ending" but at the same time the other trophy specifies "Ciel's TRUE ending".