GR translation: vessels of steel

[Mike Jing]

V702.18-28, P716.14-25   Soon he will come to know a circuit of aid
stations and field hospitals, as good for postwar nostalgia as a circuit of
peacetime spas—army surgeons and dentists will bond and hammer patent steel
for life into his suffering flesh, and pick out what has entered it by
violence with an electromagnetic device bought between the wars from
Schumann of Düsseldorf, with a light bulb and adjustable reflector, 2-axis
locking handles and a complete set of weird-shaped Polschuhen, iron pieces
to modify the shape of the magnetic field . . . but there in Russia, that
night with Wimpe, was his first taste—his initiation into the bodyhood of
steel . . . no way to separate this from the theophosphate, to separate
vessels of steel from the ungodly insane rush. . . .

What does "vessel" mean here?