A cold joke: Why did Wei Yan shout "Who dares to kill me?"

After Zhuge Liang died, Wei Yan rebelled. Yang Yi had no choice but to open the kit left by the Prime Minister, which said that Wei Yan would shout three times before the battle. Whoever dares to kill me will have his own killer. Yang Yi acted according to the plan and said to Wei Yan, If anyone dares to kill me three times, I will surrender. Wei Yan didn't know what to do, so he shouted triumphantly for three times. Suddenly, a man behind him rushed up with the horse, rapped out, "I dare to kill you", raised his knife and cut it under the horse. This man is Ma Dai.

There are many generals in Shu. Why did Zhuge Liang choose Ma Dai, whose martial arts were not top, to deal with Wei Yan?

Because Ma Dai is Ding Lin, he specializes in Wei Yan.