Marking Knife by naroe blades

165mm Long, 13 mm Wide (max), 3mm Thick, Weight 43 grams, Double-beveled sheep foot shape blade. Made from high carbon 1080 steel the Blade is hardened to Rockwell 60-61

advantages are

keep this in one of the top pockets of an apron, along with a pencil, awl, small square, and 6-inch ruler,
all operate from the bib of the shop apron
it is made from 1080 steel making it easy to sharpen to a wicked edge,
it can be gripped either with a "pencil" grip or in the palm as per a handled knife.
The flat tang means that the position of the blade is obvious, unlike a round handle knife where the position of the blade has to be "sighted" to ensure it is in the correct position, the same as scalpels or craft knives which have narrow lightweight handles as well.
The tang is a hand-forged hammer finished.
it has a double-beveled blade to pick up the extreme corner created where the bottom side of the blade of a square is placed against the surface of the material that is to be marked, ensuring the knife blade tip cannot be leveraged away from that extreme corner as can happen with a spear point one-sided bevel edge knife if it is accidentally rested against the top edge of the square blade.
In a palmed grip, it is robust enough to be held at a low angle to repeatably freehand a shallow square defined cut deeper by following the line without flex to enable a knife wall to be created with speed or to cut fibers at the bottom corner of a groove or rebate so a router plane can remove debris without snagging along the sides.
It's a knife.

Hand-made in South Australia.