Why Did Medieval Soldiers Use Halberds?

I was told that this small lever action crossbow was a Border Reivers bow from around 1600 and used for raiding and civil defence. I have never been able to find similar bows to compare it against and group it with so have never been able to know if this was true; and I still don't.

So the next best thing is to run it through some trials and practical tests and find out if I think it would be suitable. Accuracy, power, penetration, rate of fire and ability to use whilst moving.

So that is what I did.