Expertise Refurbished

Expertise, by its very nature, is limited to a specific niche. If someone is an Expert in Athletics, the natural next question is "What part of athletics?" Do the gold medal Shotput Thrower and the gold medal Swimmer have the same field of expertise? No. One is an expert in Shotput Throwing, the other is an expert in Swimming.
These rules attempt to more accurately (and more importantly, funly) reflect that reality.

Attribute (Proficiency) [Expertise]

When you gain Expertise in a skill, instead of it applying broadly to everything that skill encompasses, you must pick a specialization. There is very little limitation to what the specialization can be, but do check with your GM to make sure.
When you have an Expertise, you can write it as Attribute (Proficiency) [Expertise]. For example, swimming across a rapidly flowing river might require a Strength (Athletics) [Swimming] check. Similarly, picking a high tech lock might require a Dexterity (Sleight of Hand) [Lockpicking] or Wisdom (Crafting) [Locksmithing] check.
The idea with this is that Expertise is a specialization within a broader skill, not just a general mastery of all things.

Gaining Expertise

Whenever one of your Attributes increases to 19 or any higher odd number, you gain an Expertise in one of the skills related to that Attribute.
For example, when your barbarian gets his Strength to 19, he could get Expertise in Strength (Athletics) [Grappling]. Later, if he manages to increase his Strength to 21, he could take something like Strength (Athletics) [Long Jump].
Meanwhile, a cleric who starts with 20 Wisdom can, as part of character creation, might choose to gain Wisdom (Insight) [Body Language] or Wisdom (Medicine) [Potionmaking].

Example Expertises

Below is an example list of Expertises, but feel free to get creative and add your own.

Strength

• (Athletics) [Swimming]
• (Athletics) [Climbing]
• (Athletics) [Long Jumping]
• (Athletics) [Tumbling]
• (Athletics) [High Jumping]
• (Athletics) [Pole Vault]
• (Athletics) [some other olympic sport]
• (Athletics) [Wrestling]
• (Athletics) [Greataxe] NOTE: weapon expertise acts differently. See Weapon Specializations for details.

Dexterity

• (Acrobatics) [Tightrope]
• (Acrobatics) [Rope Swinging]
• (Acrobatics) [Tight Space Squeezing]
• (Acrobatics) [Contortion]
• (Sleight of Hand) [Knots]
• (Sleight of Hand) [Pickpocketing]
• (Sleight of Hand) [Legerdemain]
• (Sleight of Hand) [Lockpicking]
• (Stealth) [Camouflage]
• (Stealth) [Blend In]
• (Stealth) [Disguise]
• (Crafting) [Jewelry]
• (Crafting) [Tinkering]

Constitution

• (Athletics) [Distance Running]
• (Athletics) [Swimming]
• (Athletics) [Breath Holding]

Intelligence

• (Arcana) [Evocation]
• (Arcana) [Counterspelling]
• (Arcana) [Item Enchantment]
• (Arcana) [Plane of Fire]
• (Arcana) [Inter-Planar Travel]
• (Arcana) [Astral Plane]
• (Arcana) [Magic Item Identification]
• (Arcana) [Black Dragons]
• (Arcana) [Ettercaps]
• (History) [Nobility]
• (History) [Foreign Affairs]
• (History) [Names and Faces]
• (History) [Alastian History]
• (History) [The Clan]
• (History) [Cultures of Aedeva]
• (History) [Law]
• (Investigation) [Trap Finding]
• (Investigation) [Library Research]
• (Investigation) [Policing]
• (Investigation) [Ask Around]
• (Nature) [Animal Identification]
• (Nature) [Fey]
• (Nature) [Primal Magic Identification]
• (Nature) [Transmutation]
• (Nature) [Weather and Climate]
• (Nature) [Astronomy]
• (Nature) [Geography]
• (Nature) [Rainforest Ecosystem]
• (Religion) [The Wandering]
• (Religion) [Slaying Undead]
• (Religion) [Slaying Devils]
• (Religion) [Stellarian Planes]
• (Religion) [Maluuvacum Planes]
• (Religion) [River of Death]
• (Religion) [Divine Magic Identification]
• (Religion) [Healing Magic]

Wisdom

• (Animal Handling) [Horses]
• (Animal Handling) [Cows]
• (Animal Handling) [Flying Mounts]
• (Animal Handling) [Animal Training]
• (Insight) [Body Language]
• (Insight) [Read the Room]
• (Insight) [Noble Culture]
• (Insight) [Alarian Culture]
• (Insight) [Giant Culture]
• (Insight) [Counseling]
• (Insight) [6th Sense]
• (Insight)
• (Medicine) [Surgery]
• (Medicine) [Potionmaking]
• (Medicine) [Herbalism]
• (Medicine) [Battlefield Medicine]
• (Medicine) [Diseases]
• (Medicine) [Poisons]
• (Perception) [Keep Watch]
• (Perception) [Keen Vision]
• (Perception) [Keen Scent]
• (Perception) [Keen Hearing]
• (Perception) [Light Sleeping]
• (Perception) [Criminal Activity]
• (Perception) [Legerdemain]
• (Survival) [Foraging]
• (Survival) [Hunting]
• (Survival) [Trapmaking]
• (Survival) [Tracking]
• (Survival) [Herbalism]
• (Survival) [Forest]
• (Survival) [Tundra]

Charisma

• (Deception) [Legerdemain]
• (Deception) [Contracts]
• (Deception) [Misdirection]
• (Deception) [Con Artist]
• (Deception) [Secret Messages]
• (Intimidation) [Infuriation]
• (Intimidation) [Fight Starting]
• (Intimidation) [Overawing]
• (Intimidation) [Manipulation]
• (Intimidation) [Interrogation]
• (Intimidation) [Alpha Instincts]
• (Intimidation) [Command]
• (Intimidation) [Coercion]
• (Intimidation) [Subjugation]
• (Intimidation) [Grooming]
• (Performance) [Acting]
• (Performance) [Lute]
• (Performance) [Flute]
• (Performance) [Miming]
• (Performance) [Con Artist]
• (Performance) [Disguise]
• (Performance) [Oration]
• (Performance) [Dancing]
• (Performance) [Drawing Attention]
• (Performance) [Distractions]
• (Persuasion) [Haggling]
• (Persuasion) [Diplomacy]
• (Persuasion) [Manipulation]
• (Persuasion) [Grooming]
• (Persuasion) [Oration]
• (Persuasion) [Fast Talking]
• (Persuasion) [Pacification]
• (Persuasion) [Mob Forming]