Originally posted by: Chiillii
Brahmahatya was a sin at the same level as Bhruna hatya. Bhruna hatya was killing an unborn child who has no awareness. Brahmahatya was killing a scholar one who is self aware.
So no one would dare do it. That is why Kripacharya and Ashwatthama survive the war. They were attacked and disabled but never hurt fatally.
Rama had to take Agastya's help and do some puja before he could kill Ravan who was only half brahmin by birth and evil by conduct..Indra had to do severe penances to get rid of the sin of killing Vritra a brahmin again someone who was destroying life.
Even later Dhanananda does not kill chanakya a brahmin.
And Drona had done no evil. He took half the kingdom in the honorable way as Gurudakshina from.his students who also fought a fair war. So killing him was just not possible for Drupad. He would be called a sinner, his whole family ostracised forever, all brahmins will leave his kingdom. He and his descendents would also lose the right to rule.
So Drupad needed someone who had a right to kill a Brahmin.
The yagya that was done for Dhrisht and Draupadi was not a putrakameshti yagya.
The Yagya was for Drupad's son who could kill Drona a brahmin.
It was duryagya or black yagya. One done with a malicious intention. That is why every priest he goes to for officiating the Yagya they refuse, saying we will not do this yagya. Finally Yaja says I will not do it but my brother will. He is a bad guy and greedy and easy morals.
So Drupad goes to Upayaja who then does this yagya to get a divine sanction for Dhrishtadyumn to kill Drona without any sin to him or Drupad.
More like one specific group of brahmins led by upayaja took bribe and declared Drona criminal and gave sanction letter to Dhrist that he can kill him.