I’m using a Ferro relic and noticed one of my creatures had more health than anticipated. When I moved Ferro to a different creature, the new creature then had the higher health. My creatures are all using +health artifacts.
The status effect listing says Proficient does not affect Health on artifacts, but the increased health lines up with Ferro (and its auto-Proficient on weilder).
Not sure if the status effect page needs to be updated, or if Proficient is broken.