"Estoc" refers to a fairly large spectrum of thrust oriented swords. Some "estocs" are superficially virtually indistinguishable from "longswords" (which is a generic, nonspecific term that an "estoc" might be referred to as anyways), while some had a clear diamond cross-section and lacked any edge at all, with many variations in between. Obviously the Estoc we have in crpg is one that retains a cutting edge.