There's a rare occurance during battle where an enemy would cast a spell and the traps that were placed wouldn't trigger. I would just take the regular damage.
1. Huh? Did you place a Feint on someone and the other place a Feint on you? If so, the 30+ to you from your Feint is used rather then the 70+ because they're both considered as "Feints". Well... Sometimes. If they Trapped you two times, only 1 Trap activates. I'm guessing this is to not 'Spamming Over the damage maxium?' Or spamming traps.
2. Uh... I really dont know but imma take a guess. The Enemy Bladed up and Trapped really good and you put a small shield on yourself? Sometimes i will Blade and Trap really good which would cause it to do HIGHER Damge, But they put a small shield on themself Returning it to Regular or even LOWER damage.