Tom, I'm only too happy to share information with you. The article I mentioned was taken from the Georgia Weekly Telegraph (Macon, GA) August 28, 1868, Page 6, Volume XLII, No. 45. If you're unable to view the article at the link I provided please email me at firstname.lastname@example.org for a pdf file. Unfortunately, as you see, the servant is unidentified. Wm. F. Bloor of Columbus, OH returned the sword to Freeman in 1868. The only individual I can find matching his name and state is the officer I mentioned from the 25th Ohio Infantry. The Macon Daily Telegraph of October 30, 1911, page 5A creates confusion by stating Freeman's sword was taken from him by a Federal officer. Freeman died in 1885 in Oakland, CA, and the sword later passed to his sister-in-law, who displayed it on her wall along with his jacket and canteen.
My hypothesis regarding the sword's capture is in line with yours. I believe the servant was trying to desert and was captured in town. Lieut. Israel White, 25th Ohio in his after action report dated July 4, 1863, stated his regiment "remained under arms until the morning of the 4th, when it was deployed as skirmishers, and advanced through the village; then retired to its former position." Bloor stated the sword was captured on July 4.
Freeman spent some time at Camp Letterman. Junior 2nd Lieutenant Levi Humphrey Wing, Company B, was nursed at Pennsylvania College Hospital. Another soldier, whose name escapes me at the moment, was also treated at an 11th Corps hospital. Others were treated at the Second Corps hospital at the Schwartz Farm or Wright's Brigade Hospital on the Adam Butts Farm.
On another note, a Black servant with the 29th Pennsylvania was listed as wounded on Culp's Hill according to a published casualty list. If this information is of use to you I'll dig it out.