Whisperknife is a prestige class in WotC 3.5 Races of the Wild book. Is "Whisperknife" a generic name that can be used in other products or is it IP and/or protected by copywriter?
I'm thinking of a prestige class for Pathfinder using the name but creating my own prestige class build/stats.
You'd have to check the Product Identity declaration for Races of the Wild, but original names are better, if to at least avoid confusion among the audience.
how about subtle knife, silent knife, quiet knife, whisperblade, whisperedge, or any combination thereof.