Stupidity: Recurring issue when Ahsoka is fighting with dual sabers - there are often times in a duel when one saber is clashing with the other person, but she still has a hand free with her shoto that she could use to stab/slash and win the fight easily. Would make for shorter battles of course.
Part Eight: The Jedi, the Witch, and the Warlord - S1-E8
Stupidity: Despite the three heroes having four lightsabers between them, when being attacked by the perpetually-reanimating zombie troopers not once does it occur to them to simply cut their legs off, which which slow their advance considerably. Or for that matter focus on decapitating them.