New fortune cookie message: They say Rolf was left handed
"They say Rolf was left handed" - reference to wielding the artifacts
I've been playing for years, and only recently realised (after being told by another player) the massive bonus Rolf's set gets if wielded correctly. Unlike most obscure 'hidden secrets' in Adom, there are no hints to this one that I can find. I'd suggest a fortune cookie message, or maybe a statue of Rolf that specifically notes that he's left-handed, as a hint.
(Note - it's been suggested that this could be put into Thundarr's dialogue about Rolf. That's probably a better place for it, and definitely gets my vote)