Parashas Masei · Passuk 35:30 · TT note 2
Chabad.org — English translation + Rashi
Torah Temimah points to Yerushalmi Sanhedrin 7:3 (TT note on “יִרְצַח אֶת הָרֹצֵחַ”).
English: One might think: if he killed with a sword they kill him with a sword, with a stick — with a stick; it says here “vengeance” and elsewhere “a sword of vengeance” — just as there with a sword, so here with a sword.
Uniform method of execution (sword) regardless of the murder weapon.
Capital execution of a murderer is by the sword, not by matching the instrument used in the crime.