STR

STR stands for strength. It increases your character physical performance.

The damage added is based on the cast time of a skill, slow skills gain more damage then there faster counterparts.

While leveling up SPD will shorten the cast time of your skills thus lowering the ammount of damage STR adds to a skill.

You gain STR by leveling up, you get 3 STR for each increased level, you can also increase your STR from items bought at the Pawn Shop.