I don't have the artifacts to support it. But assuming I had a Codex set with low enough Crit rate rolls that I could use the R5 Battle Pass weapon on Mualani, the R5 Battle pass weapon beats out her signature weapon in damage. By a lot.

Even without using Codex and using R5 BP weapon, her Sig weapon is only like 8.6% better.

I was thinking about getting her weapon, but it's just such low value.