There are general enchant, safe enchant, untrain, and route change in Skill Enchant.
Enchant the skillThis is general skill enchant. There is a success rate and the skill will be reset when failed.
Safe Enchant
is a safer way to enchant skills. The skill won't be reset even if the skill enchant fails. Giant's Codex - Mastery is needed, and it consumes 5 times of experience points and SP.
Untrain
This returns the enchanted skill to SP. It decreases one enchant level, but recovers 80% of consumed SP. Giant's Codex - Oblivion is needed. If untrained at level 1, the skill returns to reset status.
Enchant Route Change
It changes the route of enchanted skill. A certain probability applies, and the enchanted level may stay the same or may drop 1 to 3 from the current level. Required SP and experience points to change the route of enchant skill is 20% of SP and experience points that are needed for the next level up. Giant's Codex - Discipline is required.