Recently I've gotten it into my head to get together kit for reenactment and wanted to do a 15th century halberdier. However, my research has turned up pretty empty as to how armoured halberdiers were, so it'd be a great help if anybody here has proper answers.
Fellow 15th century reenactor here, here's my main advice: have a more specified goal.
The 15th century is a large time period with lots of changes. Not only that, but the definition of "Halberdier" will change depending on where you are. A halberd could be the traditional image of halberds we have in X place, but go to Y place and it could mean some complete other thing
That's how we did with my 15th century group. We said "we want to do 15th century Pikemen" and after two years we realised it was too difficult to have something coherent, so we narrowed it down to "1470's Burgundian Pikemen". Notice how we picked a precise place and time. From there we started exploring, studying, etc. We still have a lot to work on,but overall were getting better and better
Once you picked a more precise location and time, you can start researching sources from that precise setting and it maybe easier like that, since you probably will have less contradicting sources. Sources you can look for are Ordinances, manuscript miniatures and pretty much any contemporary source like written texts or surviving objects.
Hoping this helps