[Sethomas]

"Ignorantem fortitudo est" is improper grammar, since "est" (esse in infinitive) is a linking verb and the -em denotes the accusative case. I think the right form would be "Imprudentia fortitudo est". Blanco is right about vires referring to strength, but its root is "vir" (man) which makes it more personal than that for which I think you mean.