Via Neil Gaiman’s tweeter, I think: http://www.pitbullarmory.com/Squirrel-armor.html
Possibly a fully armored mouse night? Seems out of place. Maybe he comes from outside the Territories, from a more militant mouse society. Or he’s a mouse who has decided the only way to be safe is to launch a full scale mouse war against the weasels and rides from town to town in full armor drumming up support.
On another note, that guy’s work looks pretty damn nice, and is reasonably priced, from what little I know of armour prices.
OMG, Squirrels in armour - now my life is complete!
On another note, a MouseGuard mounted upon an armoured squirrel!!! Cool. I think Gwendolyn would have liked to use these against the Weasels.
On another, other note - Night in the Museum 2, for further thoughts on mounts, has a squirrel mounted by a roman legionnaire. I think the scale for a mouse on a squirrel would be about the same, especially when they first encounter each other on the White House lawn. An interesting image is conjured up in my mind.