"Zealot" (Webster): "A fanatical partisan" , "an excessively zealous person; a fanatic" Vigilnante: "a person who takes the law into his own hands avenging a crime" Nothing really very complimentary!
Yet The Almighty calls Pinchas an "Avenger" who's zealousness restored tranquility to the Jewish People, saving them from calamity! In gratitude Hashem gifted Pinchas "Brisi Shalom" a covenant of everlasting peace and... the Priesthood of Kehuna forever!
What determines when a Zealot is a fanatic or a persuer of peace? A vigilante or an avenger?
If Moshe and his Sanhedrin didn't know what to do with Zimri, how was Pinchas so sure?
Wasn't Pinchas' great grandfather Levi chastised by Yaakov for avenging Dina in Shechem?
Why was there no need for a (anointing) process to inaugurate the new Kohen: Pinchas?
Finally, how is it that Pinchas' descendants (380 of whom were Kohanim Gedolim!) can proclaim the barcha "you have sanctified us with the Kedusha - holiness of 'Aharon' " when in fact Pinchas' holiness was independant of Ahron's Kedusha - as it was only a gift now from Hashem, after Ahron was already established as a Kohen?