The Collaborative International Dictionary of English v.0.48:

Armipotent \Ar*mip"o*tent\, a. [L. armipotents; arma arms +
   potens powerful, p. pr. of posse to be able.]
   Powerful in arms; mighty in battle.
   [1913 Webster]

         The temple stood of Mars armipotent.     --Dryden.
   [1913 Webster] Armisonant