It is quite possible that the Masonic Sword belonged to someone on your Great Great Grandfather's side of the family, so your Great Grandmother is a good place to start in trying to find out who, which Masonic Lodge and which Masonic Order. Ask other family members on your Great Grandmother's side of the family and/or do the Genealogy on the family to document the Family Tree as well but if no luck, check with the closet Masonic Lodge as they may be able to help. The Provenance of the Sword (who it belonged to, his status in the Masonic Lodge and Order as well as which Lodge and Order) can have a significant effect it's the value. The problem is with determining Provenance without a family member that can remember or records, is that many of the Masonic Lodges and Orders are now defunct, having closed many years ago. I had one fairly similar to your's and although I found out who the owner of it was (a Pharmacist in New York), I could not find what Lodge he belonged to or the Order. I purchased the sword at a combined Consignment/Estate Auction for around $75 (been a few years) and managed to sell it for $250 at a local Gun Show. With excellent Provenance, some Masonic Swords fetch fairly high prices.
Frank