Having just made his bold declaration, Leon certainly wouldn't run away, but he also didn't recklessly charge forward.
Knowing that the enemy was an adventurer team, a well-coordinated adventurer team could achieve an effect where one plus one exceeds three, capable of challenging formidable enemies above their own level.
A team with an average level of twelve could face Mielcor's Angel Envoy, the Great Demon Rafael, and shoot to kill with deadly accuracy—they spare no one once health bars are revealed, even if it's a Divine being… Well, there are some differences between games and reality, in real life an average level twelve team would still be lacking.
Games differ from reality, and the gap between people can be even larger than that between dogs; it was unclear how strong this adventurer team was, but they probably weren't bad.