Skill level
From Alter Aeon Wiki
Skill level is a percentage value indicating how well a character knows a particular spell or skill i.e. how skilled they are at using it. This is not to be confused with warrior or thief skill level which is entirely different.
How to view
Spell <spell> or Skill <skill>
Typing spell or skill on it's own with no arguments will display all spells or skills your character knows.
How it works
Each time a spell or skill is used a check is made to see if it is successfully. Skill level is one of the factors cheeked. Note: the percentage is not a true percentage check as there is an offset and even when a skill is learnt to 100% perfect it can still fail.