If Im solo on this, then the least I can do is offer some update or thoughts as I continue looking. I know the others are out there, I can hear them breathing. So far as indicated, this doesnt correspond directly with most military officers dress or court swords I am familiar with.
What is key in consideration in decoration is this curious four flamed bomb in quatrefoil. The flaming bomb is of course used as a device for grenadiers, but also for Royal Artillery and other associated units and appears to have been used in variation in some other countries as well. Apparantly there are some variations with the number of flames issuing from the bomb, in some cases up to 9, however I have not yet found variations of the flaming bomb device in multiple flames issuing around the bomb in this configuration.
The sword itself is pretty much standard configuration in officers full dress/court swords from probably latter 18th century (around the time of the infantry spadroons with backsword blades). This blade is much narrower and almost epee type in form it appears. The shellguard is atypical in that the shells project upwards, rather than flat or horizontally postioned in opposed configuration.
The period seems likely about the end of the 18th century to about mid 19th and of course certainly European, but the four flamed bomb device, which is a military oriented symbol, will be key I think. Perhaps this might be a court type sword with fraternal connections, remains to be seen.
Still trying
All the best,
Jim