That stabbing is just more curious when we realise in Poland there was no kind of "regicides" in the past centuries, AFAIK only Gabriel Narutowicz, elected president in 1922, was shot when in office as a head of state (like king or president or prime minister) or another powerful politician (notabene Narutowicz was shot by a right wing nationalist), and now the mayor of sixth most populous city of Poland very sadly joined the club.
Add Bolesław Pieracki (Minister of the Interior assasinated by the UPA) to the list of top politicians assassinated. But yes, it was in 1934, a long time ago.
Ironically, speaking of Narutowicz and "regicides", there's a powerful scene in Jerzy Kawalerowicz's "Death of a President" where Narutowicz himself speaks of no such "tradition" existing in Poland.