retund
To blunt; to make less sharp.
obsolete, transitive
Covered with skin and hair keeps it warm, being naturally a very cold part, and also to quench and dissipate the force of any stroke that shall be dealt it, and retund the edge of any weapon.
To cause to be obtuse, weak or dull.
figuratively, obsolete, transitive
to retund someone's confidence
Where it comes from
From Latin retundere, retusum, from re- (“re-”) + tundere (“to beat”).
Adapted from the Wiktionary entry retund (CC BY-SA 4.0).