Anne Wagner at the LRB:
But even the most exuberant combinations of colour, surface and texture don’t necessarily make an ordinary object a sculpture. If a handaxe qualifies, it is as both a spatial and a bodily thing. It is made to be held, and its shape declares that purpose, though in ways that aren’t easy to put into words. Imagine a two-sided tool that is also bilaterally symmetrical – something like a broad-bladed knife, though with one crucial difference. Though planar, the back of each handlaxe is is fuller than the front. There a slight bulge, a rounding, which seems both to echo and await its user’s cupped hand.
One persuasive reason to see at least some handaxes as sculpture stems from their nuanced and exacting display of formal goals. Their consistent use of symmetry is a case in point, given that such equilibrium isn’t particularly helpful where skinning prey and stripping bones are concerned. A double-edged tool doubles the risk of injury to the palm or fingers of the working hand. By these lights symmetrical axes put the threat of injury second to the pleasure presented by a well-balanced form.
These and other features help to explain not only why some handaxes seem exceptional but also why practical necessity alone doesn’t seem a sufficient explanation of their materials and forms.