Whats Affinity? What does it do? Also what's skill force?

http://onigiri.cyberstep.com/_/forum/viewtopic.php?f=10&t=3100
Affinity directly affects your attack value, which (supposedly exponentially) affects your damage output. It caps at 3000 at Lv100 and increases by 100 for every level past 100. Skill Force affects the skill force of your skills, i.e. a skill has 500 skill force, 50% skill force increases that value to 750. It appears that the 50% increase in skill force increase the final damage output by 50% as well. Multiple sources of percent Affinity or Skill Force stack additively.

To make it more simple

Affinity is how good you are with a weapon.

Skill force is the force behind your skills.