And what man that is wounded with the strook
Shal never be hool til that yow list, of grace,
To stroke hym with the plat in thilke place
Ther he is hurt; this is as muche to seyn,
Ye moote with the platte swerd ageyn
Stroke hym in the wounde, and it wol close.

– Geoffrey Chaucer

The Canterbury Tales, The Squire’s Tale. The foreign knight describes a sword whose edge will cut through any armor, but whose flat side will cure any wounds inflicted by the edge. The king of Araby has sent it as a gift to Tartar king Cambuskan.