Hand guards are mostly there for when your using a stabbing motion with enough enthusiasm to cause the hand to slip. Or to keep an opponents blade from sliding into your hand in a knife fight.

Not much call for stabbing things if your not using the knife as a weapon and such knife-on-knife fights are rare even in desperate close-quarter conflicts. Those situations are fixtures in movies and fantasy novels but not common enough to worry about in real life.

In real life the knife is much more likely to be used for housekeeping, food preparation, and general utility than as a weapon. In practical use a hand guard is superfluous and likely to get in the way. Usually it just makes the knife bulkier and heavier than it needs to be.

Skinning, scraping and carving it can be an advantage to have a knife that will lay flat so you can use the length of the edge. A hand guard tends to get in the way in such situations. As does the acute point on many spear point and false edge military designs. Usually a moderately sized single edged, drop-point knife without a hand guard is more practical.

If the worry is getting and keeping a grip on the knife because your hands are frozen a more practical solution is to have a knife with a loop of sturdy cord attached to its pommel. The loop is sized to be caught by the little finger and wrapped around the back of the hand. This reinforces the grip on the knife and eliminates any chance the knife will slide while allowing the knife to be released easily. Far more practical than any guard.

Using mittens, which don't allow access to the little finger, the cord goes around the hand first and is wrapped around the thumb once. It is a little less secure but still more effective than a guard.