It looks like a tool known as secateurs, prunning shears (long-handles) or lopping shears.
The first step would be to study how these tools are constructed. Are you wanting to have it articulate and what materials are you comfortable working with? How realistic an effect are you looking to achieve?
For starters, the pole should be quite simple, use a dowl or PVC pipe for that, there are plenty of tutorials about on polearms, but as for the shears themselves, it really depends on what you have to work with and whether you want them to articulate or not.