This picture shows an Arrow tool on the right and a Diamond perforating tool on the left.
I always understood that the single needle tool was for perforating either freehand or using the grids. The Arrow tool however does the same job though maybe not as fine.
The Arrow tool was designed to be used with the Easy Grid (mesh type grid) it can be used on both the regular and the fine mesh as it has a conical, round point. The Arrow tool makes a small round hole in the parchment, if you want square holes the Diamond perforating tool is the one you want and of course the Triangle perforating tool makes small, triangular holes. These tools work with the both mesh grids and are all made by Pergamano.
I have also used the Arrow tool successfully for making holes for brads and stippling.