Fantasy World RPG (Skill Magic System) [WIP]

The Guild ranks licensed adventurers on combat merit from F to L. Any licensed adventurer below S-Class is permitted to accept quests up to one rank higher than their current grade.
G-Class (General/Unlicensed): A baseline for anyone doing quests without an official license. It keeps the individual completely anonymous but incurs heavy monetary penalties on quest payouts. The Guild will likely take at least 50 percent of the pay for any unlicensed adventurers.
F-Class (Beginner): Restricted to basic gathering quests, pest control, and serving as porters (non-combat support carrying heavy gear and loot for higher-ranked parties).
E and D-Class (Standard): The bulk of the active guild. They handle conventional monsters and rely heavily on party tactics.
C to A-Class (Elite): Regional veterans capable of soloing large monster camps or commanding large-scale subjugation forces.
S, SS, & SSS-Class (National Asset): One-man armies serving as strategic deterrents. They handle calamity-level threats and can wipe out armies single-handedly.
L-Class (Apex Anomaly): The absolute pinnacle, standing exactly one step above SSS-Class. L-Class adventurers are living myths capable of neutralizing Godly-tier anomalies and operate entirely outside standard Guild laws.

Skills are magical or advanced physical abilities that don't typically require the use of extra magic power. Having a skill reduces any excess, unnecessary energy or power used when doing an action.

Ranked from Common, Uncommon, Rare, Epic, Legendary, Mythic, Godly, to Unique. Common is for simple things (like lighting a fire) or amateur abilities. Godly skills are typically only held by Gods and define their domain. Unique skills are beyond the power of gods, have no true quantifiable limit, and unlike all other levels, require zero mana to activate or use.

Higher ranks inherently override lower ranks through fundamentally superior mechanics, not just raw stats.
[Common/Uncommon (Utility): Bound by normal physics. Can create or direct basic energy (e.g., sparking a flame or throwing a basic fireball) but easily snuffed out.]
[Rare/Epic (Mastery): Breaks basic physics. Alters fundamental properties and achieves closed-loop self-regeneration, effortlessly outlasting and out-maneuvering lower tiers.]
[Legendary/Mythic (Pinnacle of Reality): Pushes physics to its absolute breaking point (e.g., generating self-sustaining nuclear plasma). Vaporizes lower-tier skills through sheer, catastrophic physical scale.]
[Godly (Conceptual Authority): Metaphysical rule. You don't cast an element; you govern the concept itself. A Godly user defeats a Mythic user simply by denying their magic the conceptual right to exist.]
[Unique (Anomaly): Transcends all rules. Thoughtless, instantaneous, and requires zero mana to execute.]

A sentient skill can be any tier and boosts a skill's potential up to +2 tiers. A Godly sentient skill means having a god in your soul.
Semi-Sentient Skills hold a form of intelligence, but cannot think for themselves. They can bring a skill's potential up by a tier.

Unlike standard skills that optimize mana/stamina, Curses are active detriments forced onto users by the System. The rank determines the severity of the handicap (e.g., a Legendary Curse like 'Extreme Hemophilia' makes a simple scratch a death sentence).
These skills are still unbelievably rare, with a Common Curse Skill being just as rare as an otherwise Epic Skill.

All intelligent life on this world evolved from a single ancient, non-magical ancestor. While thousands of years of evolution gave them wildly different traits, sizes, and adult lifespans, that foundational 18-year maturation period is deeply hardcoded into their base DNA and never evolved out.