Corbels are projecting blocks of stone built into a wall to carry weight, though here their function seems as much symbolic as structural. The upper one carries what is classified as an exhibitionist figure, a category of medieval carving related to the better-known sheela-na-gig tradition, in which human figures are depicted in sexually explicit or bodily exaggerated poses. The one directly below it is stranger still: a carved human figure appears to be emerging from the stone itself, head and two arms visible, the rest of the body implied but unseen.

The lower figure is worn to the point of fading. Its eyes are hollow, the nose rubbed smooth, and the mouth reads as downturned, giving it an expression that is hard to read as either threatening or merely sorrowful. The dexter arm, that is, the figure's own right arm, is tucked beneath the chin, while the sinister arm appears to support the body that never quite materialises from the wall. The carving is not strictly contorted in the way that some exhibitionist figures are, with limbs twisted and splayed, but it belongs to the same broad tradition, one that appears across Irish and wider European medieval ecclesiastical architecture and whose precise meaning has never been settled. Apotropaic protection, fertility symbolism, and moral warning have all been proposed, often simultaneously. The church at Knockgraffon is itself a site with considerable medieval fabric, and the incorporation of these figures into its fabric suggests they were regarded as part of the building's fabric rather than curiosities added later.