It's a shame if Beelzebub has been permeantly lost, that very much feels like Rimuru's signature move to me. So I'm hoping it hasn't been lost but just "used up" for a while, and that got losst in translation.
It's funny 'cause earlier we find out that Rimuru got Uriel from analyzing Unlimited Imprisonment when he released Veldora. That skill supposedly is the ultimate skill for barriers and covenants. He 100% coulda tanked it with Uriel without any sacrificing of skills
But Raphael is being a little sneaky goof probably wanted to analyze the melt slash