Captain and Knight (presumably of the Russian Order of St. Anna) "Scherdinskij", also spelled "Skyrdinsky", is mentioned in documents in Swedish, in 1821 and 1822, as "platsadjutant" (place aide-de-camp) at the Castle of Kastellholm at Sund in Åland (Finnish archipelago).
It should be noted that both Swedish spellings mean that the name starts with an English "sh" sound, as in "should", though it might be a sounding "sh".
The Polish spelling of this obviously Polish name would be different. The Swedish spelling version may be a translitteration from the Russian, which would have a special letter for this sound - whether it be a plain "sh" or sounding.
Also the wovels may originally have been slightly different, since the namne could have been written down only after it has been spoken to the scribe.
If he was, as might be expected, a Russian officer, traces of him may be found in one of the Russian Military academies. Maybe there were also Polish ones?
Posted as a aide-de-camp(probably to the "place major", i.e. the commanding officer of the Castle of Kastellholm) he would have been an artillery officer - at least that is my guess.
Any information on this gentleman would be greatly appreciated.