What does ares mean when he says percy "doesn't have what it takes"?

our founding fathers introduced the revolutionary idea that each person's desire to pursue their idea of happiness was not self-indulgence, but a necessary driver of a prosperous society. they created a government to defend that right for everyone.

- "the die is cast; i have consented to return if we are not destroyed. thus are my hopes blasted by cowardice and indecision; i come back ignorant and disappointed. it requires more philosophy than i possess to bear this injustice with patience. i have lost my hopes of utility and glory; i have lost my friend."