If I remember correctly, a "cheeser" in our neck of the woods was a conker that hadn't developed properly, leaving it with a flat side & (usually) a sharp edge on the shell, which was considered to give an advantage in terms of dealing out damage for as long as it lasted. Plus they were usually smaller & therefore more difficult to hit...

Vinegar & baking were out, as was stampsies (& I've never heard of 'windmills'). As for adding your vanquished foe's victories, I thought that was standard practice? I find it difficult to believe you could get a "fifty-er" without using illegal "performance enhancing" techniques! Only nacheral conkers roun' our way, mate!