it occurred to me that a version of this without a pointed tip- would still be extremely effective for SD and probably legal in many more places.
In CA under state law (many locations have various more restrictive local ordinances) any size blade can be carried openly. Folders concealed.
Batons or flails and other blunt instruments are illegal felonies, but if it has a blade then it is legal.
If it is concealed then a fixed blade is only illegal if it is usable as a stabbing instrument. For that reason it is technicaly legal to carry a concealed flat tipped machete/cleaver or hatchet/axe etc in CA, but a wooden stick with a handle (or a concealed screwdriver carried as a weapon) is a felony.
So under CA law you would actualy want to insure it was sharpened so it would qualify as a legal blade rather than an illegal sap, billy etc blunt instrument.
Further, with a setup that the handle was visible, if not tucked under a shirt, it is arguably a legal sheath or scabbard on a belt, just horizontal rather than vertical. So with a tucked in shirt this thing could be legal as long as it is sharpened.
Since any fixed blade, even a stabbing instrument, can be carried openly from the belt in CA it could be legal if the sheath or scabbard was not concealed. Then it is technicaly just a blade carried in an open legal manner.
(Though I would not want to be the one depending on that court case to prevail, especialy since the marketing is that of a concealed weapon, even if legaly it is not concealed under the law.)
Sometimes it is amazing how much the law can contradict common sense. Giant broadsword that can cut a man in half? Legal per state law carried openly. Remove the blade and attach a wooden dowel to the hilt? Felony.
Be sure to know your laws.