Xia Nan's Profession Level was seriously out of step with his actual combat strength.
Under normal circumstances, a steady, solidly grounded Level 3 Warrior should have been the backbone of some veteran adventurer party. His position in the team would be neither high nor low; he might occasionally overperform when the situation suited him, but most of the time he would fight around the team's backline damage dealers.
Take the Murloc Grotto before them, for example.
They were facing a group-type enemy force led by a Shahua Merman Priest with a Challenge Rating of "2," made up of nearly twenty Shahua Mermen with a Challenge Rating of "0.5."
A four-person adventurer party with an average Profession Level of "3," a reasonable lineup, and ample preparation really might not be able to end the battle without taking any damage.
After all, there were too many enemies, and there was even a Spellcaster-type among them. Level 3 was only the very beginning of a profession path; their Feats, Combat Skills, and even their physical qualities were all still lacking. They had not yet reached the qualitative change that would allow them to "ignore numbers."
Only if they had drawn up a complete plan in advance—including terrain, battlefield style, surprise Decapitation Tactics, and clearing out the fodder—and guaranteed that no accidents occurred during execution, with everything exactly as expected, would it be possible to win unscathed.
Otherwise, taking some injuries in battle was inevitable.
But if a Level 3 Xia Nan were stuffed into the adventurer party as well, the situation would be completely different.
The exaggerated mobility granted by [Tooth Hunt] allowed him to break through the enemy fodder's obstruction in an extremely short time and attempt to cut into the backline;
And the stacked Combat Skills of [Whirlwind Slash] + [Gravity