Wargame counters sometimes requires tools. Corner clippers or tweezers are popular. Sometimes a good X-Acto knife helps when cutting them out.
Recently I was looking to craft my own counters. At the same time I was punching out a wargame and was looking at the tufts not at the corners, but along the edge. Both demanded a new tool.
Behold the Fiskars 28mm Rotary Cutter. Perfect for trimming counters from their tree.
Feature image courtesy RMN
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Rocky Mountain Navy Gamer 
I use an OLFA 45mm myself.
I think that because there is a longer blade surface (141 mm vs. 88 mm) it won’t go dull as quickly when cutting through the same amount of cardboard.
But maybe I am fooling myself.
I debated between the 28 and 45mm blades but settled on the smaller one because it felt more deft in the hand. Maybe the 45mm is better for counters, especially thicker ones…
I use mine for cutting out my DTP counters which are in a solid block. Your smaller one might be better for freeing diecut ones from their frames.