The adjustable thing looks like maybe a depth gauge.
The main point is not a chisel (so not a burin), it looks more like a pick for digging into something a bit soft.
I first thought of a pick for a horse hoof, but the adjustable element precludes that.
Then I thought of a leather-working tool, but it is not a pair of compasses. The point is in the wrong place.
So maybe a tool for a mason, or builder to get the top course of bricks/blocks even, when the underlying layer is not even.
It looks like a work tool of some kind. What trades might use that?