retund means to blunt; to make less sharp.
Etymology
From Latin retundere, retusum, from re- (“re-”) + tundere (“to beat”).
verb
- To blunt; to make less sharp.“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.“to retund someone's confidence”