The Collaborative International Dictionary of English v.0.48:

Pawner \Pawn"er\, Pawnor \Pawn*or"\, n. (Law)
   One who pawns or pledges anything as security for the payment
   of borrowed money or of a debt.
   [1913 Webster]

Bouvier's Law Dictionary, Revised 6th Ed (1856):

PAWNOR. One who, being liable to an engagement, gives to the person to whom
he is liable, a thing to be held as a security for the payment of his debt
or the fulfillment of his liability.
     2. The rights of the pawnor are to redeem the pledge, at any time
before it is sold.
     3. His obligations are to warrant the title of the pledge, and to
redeem it at the time agreed upon. See 1 Bouv. Inst. n. 1045.