Although Gage couldn't survive an attack from a magical beast, this was only based on the assumption that he was still a Master mage.
However, considering what Cyneah said before, when beasts chased her, and Gage managed to kill one by himself, Kyran had to reassess his initial thoughts.
Cyneah might not have specifically said what type of beasts had chased her, but considering they had relentlessly pursued her, with one even going so far as coming after her when she fell down a gorge, they were all feral.
If that was the case, for Gage to have killed one meant his combat and magic prowess was already way beyond a Master.
For the record, the lowest mage level Kyran encountered in Somuli was at Grand Master. Hilam and his team were at that level. As for most of the Eidums defending the borders, they were Exalteds.
