A-þwǽnan

According to the Old English Dictionary:

a-þwǽnan

p. de; pp. ed [a away, þwǽnan to soften, diminish] To soften, diminish, lessen, abate, take away; diminuere, demere :-- Seó sealf wile ðone swile aþwǽnan the salve will diminish the swelling, L. M. 3, 39; Lchdm. ii. 332, 25. a-þwænan