'Whew, this leaves quite a significant dent in my aura reserve!'
Using aura to boost the kids earlier than fighting a bear by mostly relying on his aura, Matthew's aura reserve was certainly far from being full.
Matthew had been constantly keeping in check his aura reserve the whole time he was fighting the bear since it was literally his lifeline. Using his aura, Matthew had strengthened his body and created solid aura gauntlets to enable himself to defend against the bear's attacks and keep up with the bear so that he could have an even fight with the bear.
Without his aura, he will be going back to being a slightly stronger kobold with longer claws and hard scutes as an additional defense. Which is certainly not enough to fight against the bear who's able to defeat a kobold with a single nice slap to the kobold's body, particularly if it hits the kobold's head.
