Incompetent
From NsdWiki
Expoint Bonus: 2/skill
You just plain stink at a designated skill. You take a −2 to any roll using that skill. It helps to accept the fact that nobody's perfect, you loser. You may be Incompetent in a weapon skill, but your Incompetence encompasses all weapons of a certain type: swords, polearms, guns, etc.
Incompatible with
any Trump or Fault that specifically boosts the skill in question as a primary function — GM's judgment