Stat points are used when determining what you are able to use. They are not used for direct roleplaying but instead when you purchase and use runes or weaponry. Below is a run down on what stats there are, and what they are used for.

Stats:
Strength: How strong your character is, determines the ability to hold two handed weapons, and heavy things.
Speed: How fast and agile you are. Used for things like Bows and quick moving weapons.
Endurance: How you can deal with heavy things, and keep going. Used for heavy armor and larger weapons.
Energy: How well you can make use of your inner strength to use weapons with effects.
Skill: Used for weapons that are really difficult to handle.
(Unique class stat smile Used for your ability and upgrades for it that are not based on your rank.