In 25:12 Pinchas gets rewarded with Hashem saying, "הנני נותן את בריתי שלום"
Pinchas received the Nobel Peace Prize, so to speak, from Hashem for his actions.
It is ironic that the award of Peace is given to Pinchas when his action, righteous as it was, was one of extreme violence. The award would perhaps have been more appropriately called something else, perhaps the Plague Prevention Award or the Standing up for God Award, or whatever. But the Covenant of Peace?
שלום is not necessarily pacifism - always looking to talk through your disputes and arguments. Sometimes to achieve peace, a violent act might be needed.
It takes a bold and daring man to recognize that. Pinchas recognized that this situation, this public defilement of the nation, could not be resolved by discussion and persuasion. Only by one method would the situation be resolved. His violent act killed two people, but it spurred the Jewish people on to renewing their relationship with Hashem.
That is why Pinchas, despite, nay - because of, his violent act, won the Nobel Peace Prize.