On the republishing of crit tables, It appears that something is slightly altered, each time.
The group has used Arms Law #5520 for years. Ours is a bit cumbersome because of sheet protectors and heavy notebook.
#5520 does have different crits built into the roll; puncture, slash and crush from a broadsword, for example. Where #5810 has the smoothed, easy to read tables, but less variety in damage/crits. You can do different crits in the newer book, but there's something to the variety of the old book.
Also, the crit tables are on the back of each weapon, but that may just be how the group printed it. So there is less book flipping.
I like Arms Law #5810 because it's easier to handle (and read!) while running a game.
The hits for weapons are nearly identical in both so it doesn't upset the game too much, but there are differences.
There descriptions for crits can vary, too. One book may be more descriptive than the other, but the damage, stun and penalties appear the same.
It's worth considering if such a book is ever printed. Just saying.