The Collaborative International Dictionary of English v.0.48:
Advantage \Ad*van"tage\, v. t. [imp. & p. p. Advantaged; p.
pr. & vb. n. Advantaging.] [F. avantager, fr. avantage. See
To give an advantage to; to further; to promote; to benefit;
The truth is, the archbishop's own stiffness and
averseness to comply with the court designs, advantaged
his adversaries against him. --Fuller.
What is a man advantaged, if he gain the whole world,
and lose himself, or be cast away? --Luke ix. 25.
To advantage one's self of, to avail one's self of. [Obs.]