use the 2 charts here:
http://www.geocities.co.jp/Playtown-...371/skill.html
you actually can raise skill with TW mobs provided they are not too weak in relation to your skill. for example, let say your dagger skill is 20 which would be cap for level 7. If you fight mobs that would give xp for a level 7, you can still skillup your dagger, even if they check as TW regularly to you.