Informal Training (3.5e Flaw)
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Though you learned the basics of fighting, you lack the skill and flexibility to apply your techniques properly in battle. When faced with a situation you didn't train for, you don't know what to do.
Effect: Whenever you are subject to an attack with a weapon you are not proficient in (including natural weapons), you are considered flat-footed and therefore lose any and all dodge bonuses to AC against the attack, including those provided by fighting defensively or total defense.
Special: This flaw overrides uncanny dodge.
Roleplaying Ideas: A character with this flaw might be self-taught, or have only limited tutoring in regards to fighting. It is especially appropriate for nobles, or characters who are otherwise accustomed to highly regulated forms of combat. When faced with a situation where they are deprived of their bonus to AC, a character with this flaw might take such actions as to panic, flail wildly, or complain about the unfairness of their opponent.