G10 and carbon fiber handles to compare
G10 and carbon fiber are not always either-or: Kershaw lists one model's handle as "G10, carbon fiber overlay front," and CIVIVI lists one as "Twill Carbon Fiber Overlay On Black G10." Between the two laminates, UltreX names glass fibers as G-10's "primary difference" and says its carbon fiber "tends to be slightly lighter than G-10, canvas or linen."
UltreX, which offers both laminates, calls G-10 similar to Micarta and carbon fiber and says "the primary difference is G-10 uses glass fibers." Kershaw calls G10 an "epoxy-filled woven glass fiber."
A carbon fiber handle is also fiber in resin, by its makers' descriptions. Kershaw says carbon fiber atoms are "bonded together in crystals aligned in long strands, then woven together like fibers," then set in resin, and Böker describes "extremely tear-resistant carbon fiber mats embedded in a matrix of epoxy resin."
Carbon fiber overlay is spec wording on a Kershaw page and a CIVIVI page, and neither defines the term. Kershaw lists one model's handle as "G10, carbon fiber overlay front" and describes it as "all-weather G10 with a carbon fiber overlay"; CIVIVI lists one model's handle as "Twill Carbon Fiber Overlay On Black G10." Read as written, both name G10 as the handle and carbon fiber as an overlay on it, not a handle that is carbon fiber throughout.
Some product descriptions on this site use the same overlay wording, and none says how the overlay is built. UltreX's "carbon fiber interleaved with colored G-10" is a separate construction of its own, not the overlay these makers list.
The makers praise both laminates, and none ranks them for toughness. Kershaw calls carbon fiber "extremely strong," Böker calls it "extremely strong and yet very light," and CIVIVI calls it "highly durable and resistant to impact, corrosion, and wear." On the G10 side, CIVIVI calls G10 "a dense, durable material," and Kershaw says it "makes excellent handles and handle scales for knives." Upkeep for carbon fiber is the subject of caring for a carbon fiber handle.
That leaves the choice to the traits the makers do state: UltreX's line that its carbon fiber "tends to be slightly lighter," given without a figure, and the look of a woven or marbled carbon fiber surface, against a G10 handle Kershaw calls "extremely stable, unaffected by temperature changes."