Do curses or ability damage/drain cause a character to be unable to use his feats?
For example, a Ranger with 20 Dex who has two-weapon-fighting feats and is using two weapons gets cursed or ability drained and his Dex drops to 14. Does that cause the character not to be able to use his two-weapon feats (which have a requirement of at least 15 Dex)?
What about his other feats that have prerequisites of blocked feats? (As another example: a fighter with the Whirlwind Attack feat, which requires Combat Expertise gets an INT penalty that drops his INT under 13, a prerequisite of Combat Expertise). I think that he can no longer use his Combat Expertise feat (because of low INT) and also Whirlwind Attack and any other feats that require Combat Expertise. Is that right?
I guess it is better to clarify the reason I am asking.
First of all, there are so many books, and there are too many authors that create them and test them. Many bugs are uncovered due to that reason. It is quite hard to keep track of all these things. I know that.
The reason for the question is, for higher-level builds, skill, feat, class, prestige class, template and ability score choices become more important. And there are casters, whose main combat skills depend on spells (clerics, sorcerers, and wizards, especially). Maybe druids can deal with key ability score penalties, and clerics may try to survive such conditions. Wizards and sorcerers have less of a chance when their key ability score drops. A curse may cause them to be without magic (or with some weak spells) if they fail to resist it. They probably have higher Will saves, but they all have the chance.
And I am trying to be sure about the situation of a warrior-based class, because feats mean a lot to them. So what happens when they get cursed? Failure to be able to use a key feat is important, but not as much as a wizard who is unable to cast spells.
Related FAQ answer is not enough about this situation (the following part)
A feat sometimes requires you to have a certain ability score, which is the case with Two-Weapon Fighting (it requires Dex 15). A character has, say, Dex 13, but wears an item, in this case gloves of Dexterity +2, and now her Dex score is 15. Can she take the feat and have it be active only when she wears the item?
Actually yes, she could take the feat, but she would lose the use of the feat if, for whatever reason, she loses the bonus from the item.
So, still looking for something more satisfactory.
UPDATE: @LitheOhm's answer:
*Two-Weapon Fighting *
Prerequisite: Dex 15.
Oversized Two-Weapon Fighting
Prerequisite: Str13, Two-Weapon Fighting
I wish to clarify that, I just wish to be sure about what to do in such situation. That is just an example and probably being able to use
Oversized Two-Weapon Fighting feat will not save the character while he could not use basic
Two-Weapon Fighting feats due to Lowered DEX. But I still wonder, whether he could still use
Oversized Two-Weapon Fighting.
Of course there could be some other feats which fits that situation. That is just one I noticed.