SCH Master levels do not increase magic skills under the effect of Arts.

[Voidstorm]

Platform: PC
ISP: Spectrum
Type of Internet Connection: FIOS
Internet Connection Speed: 200Mb
Date & Time: Nov. 25
Frequency: always
Character Name: Voidstorm
Race: Tarutaru
World: Ragnarok
Main Job: SCH
Support Job: WHM
Area and Coordinates: Alzadaal Undersea Ruins
Party or Solo: party
NPC Name: none
Monster Name: none
Steps:
Use Light Arts or Dark Arts. Skills boosted my arts that had increased due to increasing Master Level increases to the same it was when I had Master Level 0. (420 & 456)

[Voidstorm]

Hm, maybe better wording for 'Steps:'
Under the effect of Light Arts: Divine, Healing, Enfeebling, and Enhancing Skills unchanged M15 v M0. Likewise for Enfeebling, Elemental, and Dark skills under Dark Arts.