ARHANGEL is a compressed archive utility for DOS, and its native .LG file format, developed by George Lyapko (also written "Lyapko George"). It was distributed as shareware. Its name is derived from "ARchive HANdler by GEorge Lyapko".
Based on the warnings in the change log, you probably shouldn't expect much compatibility between different versions.
Files created by v1.40 start with ASCII "