The brahmanas are not encouraged to fight or kill. No. They should remain always nonviolent. Even there is required violence, a brahmana will not kill personally. He will bring the matter to the ksatriya, royal order. Just like Visvamitra. Visvamitra was being disturbed by some demons in the forest. They used to live in the forest. So Visvamitra was able to kill such demon, many demons, by his will. But he did not do so. He went to Maharaja Dasaratha, father of Lord Ramacandra, to request him that "Give your sons Rama and Laksmana. I will take them with me. They will kill that demon." The killing is there, but the brahmana is not going to kill personally. Or the vaisya is not meant for killing, neither the sudras. Only the ksatriyas. The ksatriyas should be so trained up.
Lecture on Bhagavad-gita, London, September 4, 1973