Strength = Weapon damage, carrying capacity, block (skill) chance and to ]grab weaker targets. Also used as a pre-requisite to equip certain items (armor, weapons, shields).
Dexterity = Swing speed, hit chance and defense chance.
Intelligence = Spell damage, skill gain rate and mana regeneration (via meditation skill).
HP = To stay alive, don't let it go down to 0!
Mana = To fuel spells, weapon special attacks and certain class abilities. Also used as a resource to craft spell scrolls (via inscription).
Stamina = Swing speed, dodge (skill) chance and to fuel certain class abilities.
Luck = Improves chance for artifacts when digging up treasure chests (via cartography skill), improves chance for enchanted jewelery crafting (via tinkering) and improves chance for alchemy scrolls to drop as loot.