From the July 23,2017, Washington Post by Mark Pratt, AP.
Robert Gould Shaw, who like all officers in black units, was white. After he was killed at Fort Wagner he was stripped of his clothing and belongings by Confederate soldiers. His sword was recovered about two years later from a Confederate officer and returned to his parents.
(So, here, the sword was either recovered by a Confederate officer and returned to Shaw's parents or found in the possession of a Confederate officer, confiscated and returned to his parents.)
The sword's serial number matches the records of its maker, English swordsmith Henry Wilkinson.
It is tarnished and has some rust on the blade. There is also some wear on the handle even though Shaw had acquired it only a month before his death and used in battle just twice.
The blemishes on the sword are likely the result of a Confederate officer using this highly valuable sword for the rest of the war.
It is a very superior sword.