Shell small for the subgenus, up to 11 x3.7 mm, elongate-fusiform, rather thin, smooth, shining. Protoconch hemi-ellipsoidal, multispiral, 0.60 mm in length and 0.55 mm in width at the base, consisting of 3.0 to 3.5 smooth, slightly convex, transparent, light yellow or amber coloured embryonic whorls.
Teleoconch with 7 slightly convex whorls, sutures distinct and impressed; whorls slightly shouldered at the sutures, out-line of early whorls slightly concave. Dominant sculpture formed by slender and smooth axial ribs, which number 15-17 on the first, 18-20 on the penultimate, and 25-27 on the body-whorl. Ribs becoming obsolete at the periphery on dorsal side of body-whorl, but slightly nodulous on all whorls just below the sutures. Weak spiral sculpture formed by fine grooves in the interspaces of axial ribs; grooves do not bisect the ribs of spire-whorls. Grooves numbering 6-7 on initial whorls, 10— 11 on penultimate whorl, and 18-20 on body-whorl; at the constricted base of body-whorl the spiral grooves are more widely spaced and bisect the axial ribs, resulting in 3-4 nodulous spiral cords. Siphonal fasciole formed by 7-8 flat, oblique, axially striate, densely arranged cords.
Aperture shorter than the spire (40-44% of total shell length), approximately 1 mm wide, scarcely constricted anteriorly, with 10-11 weak and slightly nodulous lirations inside; lirae ending at some distance from the edge, leaving the inner side of the outer lip smooth. Outer lip predominantly simple and smooth, slightly crenulate only at the anterior part; siphonal canal relatively long, wide, and distinctly recurved to the dorsal side. Parietal side of aperture with a fold-like callus near the posterior aperture angle; inner lip distinct, strongly protruding only in senile specimens (e.g. paratype 2); columella with four plaits decreasing in size anteriorly.
Ground colour light beige, initial 2-3 spire whorls uniformly white or beige, later whorls with a continuous light brown subsutural band, and lower part of body-whorl with 1-2 zones of light brown stains between the axial ribs. Siphonal fasciole, aperture and columella light beige.

Vexillum (C.) fraudator is very similar to Thala maldivensis in size, shape and colour, but lacks the denticles found on the inside of the outer lip of most Thala species. The columella has only 4 plicae, instead of 5-6 as in T. maldivensis, and there is a fold-like parietal callus near the posterior apertural angle, which is lacking completely in T. maldivensis. In addition, V. (C.) fraudator is more prominently sculptured, especially between the axial ribs, and it has more elevated and slender axial ribs

Known from East Africa (N. Mozambique), the Maldives, Marianas (Guam), Papua New Guinea (New Ireland), Solomon Islands, New Caledonia, Marshall Islands (Kwajalein), Samoa, and Tahiti. Subtidal, at 2-35 m, on a bottom with coral rubble and rocks (partially in caves of reef drop-offs).