The Collaborative International Dictionary of English v.0.48:

Peen \Peen\ (p[=e]n), n. [Cf. G. pinne pane of a hammer.]
   (a) A round-edged, or hemispherical, end to the head of a
       hammer or sledge, used to stretch or bend metal by
       indentation.
   (b) The sharp-edged end of the head of a mason's hammer.
       [Spelt also pane, pein, and piend.]
       [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Piend \Piend\, n. [Cf. Dan. pind a peg.]
   See Peen.
   [1913 Webster]