Daniel C. Plaster, 41, 534 Upper Sand Valley Road, Jonesborough, was arrested following the incident at 1910 Triangle Road.
Police said Plaster called to report trespassing, but the alleged trespasser was Plaster's live-in relative and was lawfully at the Triangle Road property.
Plaster and his relative had been in a heated argument, police said, and Plaster displayed a pistol during the dispute. The victim told police Plaster put the gun in his face, and a witness was present.
Plaster was charged with aggravated domestic assault. He was jailed in the Washington County Detention Center with a Sessions Court appearance scheduled for Monday. His bond had not been set.