Curse of the Dead Gods

This is a matter of luck but you can increase the odds.
First you can upgrade your weapon altars to the max level. Then you have a chance to start with a cursed weapon.
The best exploration is probably the pantheon since you can go for the champion weapons as well as the weapon rooms. As soon as you have 2 cursed weapons i would try to either get a champion weapon which fits in the last spot or find a weapon room and shuffle through the options with divine favor. Even with this tactic it will still take a few runs to get. But if you keep trying it will happen eventually.