So many reasons not to use an Opinal for gralloching, hygiene being top of the list with all the bits you’d collect in the locking ring and handle. Carbon steel definitely has its place and I do own some hunting and kitchen knives made from it - keep them dry and lubricate with food grade mineral oil. The Opinel has a very fine thin grind which id say is unsuited to the task, but would quickly sharpen up mid use with a steel.