What Micheal FtW said . . . All of it . . .
I live on the Oregon Coast, around a fair number of fishmongers. The Health Dept. and commercial fisheries requires that handles/grips/scales on a knife be seamless, stable, non-reactive, and non-porous. That pretty much leaves plastic and variations in plastic.
Commercial knives in this realm have all the features of a fine knife -- good steel, full tang, bolster in the larger blades -- but the handle is molded plastic.
Brand names preferred locally are Dexter-Russell and Forschner. I pick up knives in thrift shops that come from canneries, fish markets, etc. I have a 6" filet, Dexter-Russell that I picked up in a flea mkt for $3. Lots of life left in it.
The local marine supply sells Dexter-Russell in carbon blades with hardwood, riveted handles. These don't get into the commercial plants, but my 8" "butcher" utility is the sharpest knife in the block.
Anyway, before you visit the "designer gourmet cooking shop" . . . head into some commercial suppliers of hotel and restaurant equipment -- or the local marine supply shop.
The best knives I own are commercial grade work-horses. Plastic handles, carbon blades, full tang, bolsters on the larger blades. Nothing fancy, but sharp, well made, well balanced, durable.