It sounds like a hand carved "endearment" or "friendship" ring. It could have been used to show his intentions at a future date, like when this war is over. I have heard of rings carved from wood and bone for this useage and that usually there were two rings, one for him and one for her. That's the type of heirloom you want to hang onto.

The "F.E.A." should be his intended.

JR