From "The Evolution of Arms Law (1980-2003)" by Brent Knorr:
In April 2003, a new version of Arms Law was released for RMFRP, the first product to use the new Rolemaster logo.
This version of Arms Law is an 80 page saddle stitched book instead of a 120 page square bound book like the previous version. Most of this space is gained by not including the half size Critical Tables on the backs of the Attack Tables. The reduced page count also keeps the price down to $16.00 instead of being in the $20.00 to $22.00 range.
The Introduction covers what Arms Law is and how it is trying to simulate combat situations as “believable fun, not drab realism.” It also describes what is new in this version of Arms Law.
This is the first version to actually change the attack tables, replacing the single number progression used in previous versions with a smoothed progression, i.e. 67-69, 148-150. This is the same way the Attack Tables for Spells are done, as well as the Attack Tables for Spacemaster.
This style of table was also use in The Armory, an Arms Law supplement, which was released in 2002. The Armory had also introduced the idea of a weapon having a primary critical such as Slash and for many of the weapons, one or two alternate criticals that the attacker has the option of choosing. The choice must be made before the attack roll is made, and there is set penalty ranging from 5 to 30 points that is subtracted from the attack roll if the alternate critical is selected. This is also used for many of the weapons in this new version of Arms Law.
Another change is that the weights and lengths of some of the weapons have been adjusted after comparison to historical weapon weight and lengths.
The flavour text of the criticals has also been updated, returning to the more “interesting” style of the earlier versions of Arms Law. The actual game effects of the criticals remain the same to preserve compatibility with previous versions.
Section 1.0 is “How to use Arms Law”, which gives descriptions, definitions and tables relating to some of the terms used in the book such as Defensive and Offensive Bonuses, Armor Types, etc. It’s basically the same material that is described in previous editions. It includes three full-page charts with Weapon Statistics, Animal Statistics, and Monster Statistics.
Section 2.0 is “Making an Attack” and it runs through how to use the Attack Tables and the Critical Tables. Section 2.04 is the new section on the Optional Criticals and is the one section that players familiar with previous editions of Arms Law and Rolemaster should read.
This is followed by the Attack Tables, these cover the same Weapons and Attacks as previous versions, 29 Weapon Attack Tables, 13 Special Attack Tables, 12 Critical Strike Tables, and 2 Fumble Tables. The Special Attack Tables have not changed at all since the previous version of Arms Law. I was a little surprised that the Weapon Attack Tables and the Special Attack Tables still have the results columns in opposite order. I thought that since the Weapon Attack Tables were being redone anyway, they might take the opportunity to switch them from going from the highest number at the top of the page and the lowest number at the bottom, to being lowest at the top and highest at the bottom to be consistent with the Special Attack Tables.
There is an unfortunate error that has made its way into the Critical Tables in the first printing of this version of Arms Law. A “1” accidentally got inserted before critical results that indicate a negative modifier. This implies that the penalty would only last for one round, which is not correct.
So when it says “1” preceded by a negative modifier ignore the “1”, the penalty lasts until the wound is healed. For example, the last line for a 66 result in the “A” column on the Brawling Critical Strike Table says “+8H-6*-1(-15)”. This would be read as “8 additional hits, 6 rounds of Stun, -15 penalty for 1 round. It really should be a permanent -15 penalty until healed. ICE has promised to post a pdf file with the corrected charts on their website, it should be available by the time this article is published.
The last section of the book is “Converting to Arms Law from Other Systems”. This is a three page section that covers how to use Arms Law with Dungeons & Dragons Third edition (D20), Advanced Dungeons & Dragons (which I suspect would work with Hackmaster as well), GURPS, Legends of the Five Rings, Werewolf: the Apocalypse, and other Dice Pool Systems.