I'm no pro knife maker so usually work with high carbon steel already hardened and tempered.
I've used chainsaw bars and large steel blades from industrial hack saws as well as circular saw blades. Maybe a mower blade once.
One blade was cut from an old thick handsaw.
Steels vary as to their qualities when hardened and tempered. One thing to consider is size of stock if wanting to acquire a piece...
Yours would need lots of reduction with multiple cuts to make blades.
Easier to buy stock nearer to desired blade thickness.
Your piece looks like a piece of scrap mild steel someone practiced on by engraving a monogram on it. They did pretty good who ever did it.
At a market it could mark a vendors spot or hold a tablecloth down,papers/bags /flyers ect.. or be part of a craftsman's demonstration from a previous event?
Good eye spotting it though.
Worse case it was needed to claim a scavenger type hunt prize.

Edit; my slow pecking away and missed austin's post till after...