"I wielded them as a god." You used your powers to try and impress the personification of death in a bid to get in her pants. Then threw a hissy fit when she shot you down, and a R63 version of yourself to fuck.

I'm really not sure if Thanos should be the person to talk about how to use god-like power.

I think that's kinda the point, given that Doom just tore him to shreds