Aes Sedai (semi-spoiler)
If it takes that long to cast, it's a wonder how they even survive in the front lines. Mages should be in the back row casting their AOE high damage spells and not up front or close quarters where they're the most vulnerable. The One Power is also visible in bright white so it's hard not to go after these mages from the start.
I find it hilarious how a Trolloc threw a short sword into Moiraine's shoulder then just group stared and charged instead of throwing another short sword. She was clearly vulnerable but they instead gave her time to cast her One Power spell to boulder bash them.