Decay rate needs to be fairly fast. Maybe not begin quickly, but when it starts, it should eat through the skills pretty quickly. If they're using the skill with any sort of regularity, then they'll keep it in shape. If they're not using it, then they should fall out of practice, as it obviously isn't as important to them.

Of course, any system of decay needs to be tested very thoroughly.

Social skills are nice, but they're difficult to implement on a computer. The easy thing to do is combat.

I still think that a faster decay rate will be needed, but without testing the game, I couldn't say for sure.

Guimo, I'm going to assume "los star" was a typo of "low stat" ^^

However, I still don't really understand what you are trying to say. Are you saying that I should increase the range of reachable stats? I don't know if you realized this but in the system I have outlined above there are no levels, so any increase in attributes has a pretty big impact on character power. I could see why it would be easier to make a giant hierarchy of power levels using that kind of system, but why would I want to, wouldn't it put PvP and the game as a whole off balance?