Humans and monster are rated by Levels. The higher the level the stronger the person
One can level up by completing task given by NPC's in the tower, accomplishing something great(It depends) and by EXP.
Low Level kills don't give EXP to high Level players.
Skills are ranked by the level of mastery they have.
The longer it takes a skill to reach (Level: Max) the stronger it is.
Guilds and Ghouls are ranked the same.
Bronze
Silver
Gold
Platinum
-On Ghouls what matters is the Level not the rank
Weapons are ranked from
Common
Rare
Supreme
Legend
Epic
Mystic
Divene