To be more blessed than someone else.
It means to have more good things than someone else.
Examples:
She felt outblessed by her friend's good luck.
I think I am outblessed by my sister.
He outblessed all his friends with his new toy.
I feel outblessed when I see all the presents she got.
She was outblessed by everyone at the party.
He outblessed everyone with his big cake.