In this case, we're looking at more description than proscription.
Realize that a character with Body 10 is going to routinely roll very
Wide, and if they have Hard and Wiggle die (which any good talent with
a maxed out stat should have) they're going to garuantee wide sets.
When a wide set meets armour, sure, it gets knocked down, but how
often does a pool of 10 dice fail to damage someone behind HAR 2 or 3?
Because a body character does damage, and often, where others would
fail, it is described as doing so, not said to do so better than a
counterpart.
Similar example - an explosive is described by how well it blows
through a concrete wall. This does not mean it is specifically geared
towards blowing up concrete or destroying walls, but is given this
description because everyone knows how hard a concrete wall is.
That, however, in no way prevents a Talent from gaining Penetration on
their fists smoehow - perhaps a technique of winding up a
suiperflexible limb to provide some torque on the shot, or an aura
that weakens metal in contact with him...