[Mastery: Proficiency in Multiple Martial Arts]
The only problem with Sterl's plan was—
Once he learned an arcane skill and then enhanced it, the difficulty of training would not be low. Accumulating proficiency wouldn't be that easy.
Sterl had a strategy for this. He could continue to farm places like the Death Village to accumulate blood force.
Including [Mastery: Proficiency in Multiple Martial Arts], Sterl could use blood force to brute-force his proficiency in arcane skills.
Blood force itself could push a player's skill proficiency to a mastery level and even break through to a grandmaster level. Naturally, it could be used to increase daily proficiency. Though it would be somewhat wasteful.
So, no matter how difficult it was to train secret techniques and arcane skills, as long as he utilized blood force, he could forcefully increase his proficiency. And with skills like Starfall, Sterl's efficiency in farming monsters was extremely high, fully supporting this approach.