Can anger be spiritually useful?

The following excerpt is from a samvaad (dialogue) session with Acharya Prashant.

Questioner (Q): Acharya Ji, we use anger as a weapon and it’s a weakness too. How to stop anger from becoming a weakness and why do we get angry?

Acharya Prashant (AP): When the desire is not fulfilled Parul (Questioner) then one gets angry, you know that. So, it’s not about anger. It’s about the…