No, you're right. That heft is more like 1m (little over three feet), I'd guesstimate. Still, from the size of the axe-head it looks like a credible weapon of war to me. Even if the Danish axes were as long as you describe, it doesn't mean all battle axes had to be. You still have the pole axe with a reach of 180, that could well be the six feet axe you mentioned. The Great-Axe at length 88 should be about four feet.
Still, of course we could have better results if we rescaled the weapons individually, but that would also mean redoing the damage and speed stats (since relative size would change). In this way, by reducing all weapons by the same amount, we can keep rebalancing to a minimum.
In the next version (already half there, RCM version is completed), I did reduce the new medieval and viking swords with only to 85% (they had more realistic size to begin with) and as a result, I've had to redo damage stats for all of them. Don't want to go that way unless I have to.