Awareness covers not only perception, but also magical senses, allowing characters to pierce illusions, tricks, deception, confusion, and stealth. It's also useful for searching areas, discovering hidden items, and finding secret doors. Lastly, it's used to resist the effects of failed arcane spellcasting.
Deception is all about lying and misdirection. In social situations, it's used to get information or favors from people who would normally not want to help, therefor it always lowers standing with targets on failure. In combat, it can be used to trick opponents, giving the attacker an advantage. Deception can also be used for disguise and impersonation.
Dexterity involves both agility and coordination. It's used for acrobatics, ranged weapons, thrown weapons, picking locks, disarming traps, and combat maneuvers. Attacking with two one-handed melee weapons allows you to re-roll one die per point of dexterity.
Empathy allows a character to determine how any two individuals or groups regard each other in a social situation. When successful, it gives advantage when using other social skills against the same targets, even in battle. It's also used to determine when others are lying or disguised.
Fortitude is the measure of a character's stamina, durability, and resistance to negative effects. It's used to avoid nonlethal damage and, while wearing armor, lethal damage as well. It also protects against poison, sickness, and fatigue, as well as the negative effects of hunger, thirst, and hostile weather. Finally, it also determines how long a character can hold their breath.
Intelligence governs a wide variety of fields, including academics, alchemy, linguistics, and monster lore, but also more focused topics like deduction, riddles, and memory. It's also used to identify arcane artifacts and reduce the casting time of arcane spellcasting.
Intimidation involves getting someone to do what you want through browbeating and the threat of force. In combat, it can be used to scare or taunt enemies. In social situations, it always lowers a character's standing with the target.
Persuasion is the delicate art of convincing people to do what you want them to do. It's useful in negotiation, diplomacy, haggling, and getting information out of people or getting them to help you. In social situations, it can improve a character's standing with another individual or group.
Reflexes determines how good a character is at avoiding traps, falling damage, and, most importantly, physical attacks of all sorts.
Religion is the primary skill for casting divine spells, though it's also useful for divine implements and artifacts. It can also be used for identifying deities, demigods, demons, undead, and other such creatures. Attempting to cast a divine spell without a divine implement causes disadvantage on the roll.
Spellcraft, above all, is used for casting arcane spells, through it's also useful for using arcane implements and artifacts. Attempting to cast an arcane spell without an arcane implement causes disadvantage on the roll.
Stealth allows a character to move and act without being seen, such as when hiding, sneaking, or camouflaged in the wilderness. It's also used for picking pockets and springing ambushes on unsuspecting targets, causing significantly more damage. Once engaged in combat, it's usually not possible to use stealth to hide again. Making an attack with a one-handed weapon while you have advantage causes a number of wounds equal to your stealth.
Strength is the measure of a character's physical might and athleticism. It covers running, climbing, jumping, lifting, and swimming. It's also used for combat maneuvers and unarmed attacks like punching and wrestling. Attacking with a two-handed weapon causes a number of wounds equal to your strength.
Weaponry determines how skilled a character is with all weapons, including one-handed, two-handed, ranged, thrown, and improvised weapons. It's also used to identify, appraise, and maintain weapons. It can also be used to operate siege and shipboard weapons.
Willpower is the measure of a character's mental toughness, allowing them to resist fear, domination, intimidation, seduction, temptation, and sleep effects. It's also used to resist the effects of failed divine spellcasting.
Wisdom is a character's deeper understanding of the world around them. Beyond its importance for intuition, sixth sense, and good judgment, it's used to reduce the casting time of divine spells and identifying divine artifacts. Finally, it can be used to heal wounds once per scene.