Rządkowski is a medalist of various international championships in junior categories[3].
In 2014 he won bronze medals in both individual and team foil competitions at the Cadet European Championships (under 17) in Jerusalem. At the same location, he won a gold medal in the team foil event at the Junior European Championships (under 20). Additionally, in Plovdiv, he became the individual world cadet champion in foil.[3] In 2014, he also competed in the 2014 Summer Youth Olympics, where he won a gold medal in the boys' foil event[4] and a silver medal in the mixed team event, where he competed as part of Team Europe 1.[5]
In 2015 he won a bronze medal in the team foil event at the U23 European Championships in Vicenza[3].
In 2016 he won a silver medal in the individual foil event at the Junior European Championships held in Novi Sad[3]. At the same event, he also won a bronze medal in the team foil competition.[6]
Rządkowski has also won medals at the Polish Fencing Championships in various age categories (under 14, 17, and 20). He is also a medalist at the Polish Senior Fencing Championships, including winning the team foil event in 2013.[7]