I just tried my aircraft cable cutting plier on solid steel wire and it worked very nicely. Since this tool is designed for stainless wire, cutting through mild steel was easy.
Go to eBay and search for "
Stainless Steel Wire Rope Aircraft Bicycle Cable Cutter" and you'll see what it looks like - and unlike using a bolt cutter this is a 'bypass shear' so the cut ends are square rather than the 'crushed and mangled' ends most V-bladed bolt cutters provide.That should work well for chain mail construction.
The eBay ones are probably imports at about $25 and should last a while - (I paid a lot more years ago for a USA-made pair that are still going strong after hundreds of cuts. )
Stu