By finding manly ones. Ones who had enough confidence in themselves and their abilities (whether justified or not) that they could afford to spare some resources for others. Mercy is the privilege of the strong after all. I'm reminded of the king in Beowulf being called "Ring-giver" in praise for his generosity.

I feel the title is a bit confusing. "Moderates" here means that high testosterone reduces the impact of narcissism on generosity. High/low narcissism consistently predicted generosity for participants with low testosterone, but those with high testosterone were moderately generous regardless of narcissism levels (i.e. in between the two extremes).