How is the name Russian?
Iziaslav of Polotsk sun of Vladimir (prince of Kiev) and prince of Polotsk (Belarusian ancestor)
Iziaslav son of Yaroslav – prince of Kiev.
Other Iziaslavs lived in what is today Ukraine.
I wouldn’t say Izyaslav is ‘glorious conqueror’ . Just conqueror (Greek version of Alexander) while -slav/slava added to many Slavic names.