As I started walking towards the exit of the boss room, I heard the girl calling for some help behind me, upon which the two other frontline fighters rushed over to offer their assistance.
Standing on either side of the injured guy and wrapping each of their arms around his back, they had his arms over each of their shoulders, supporting him to his feet and walking alongside the rest of the group.
As for the mage and the archer, they were both remaining quite quiet, but they too seemed to follow along without a word.
At the end of the boss room, the huge door seemed to have a hole where one could insert something like a key. Momentarily searching around the corpse of what I presumed to be the original boss, it didn't take long to find it, and that's because I realised it was actually the giant scepter beside its fat, grubby hands.