I ran 10,000,000 simulations for 4 dice, 6 dice and 9 dice and sent the probabilities of each (block,attack) combination for both a player with the King's Guard Armor equipped and one with the Trusty Shield equipped.

I then spit out the differences. See below (click to zoom):

It certainly seems like, for the most part, the King's Guard Armor takes probabilities away from less favorable outcomes and moves them to more favorable outcomes (when compared to the Trusty Shield). This is not the whole story because of course there is always a positive probability of no shields with the King's Guard Armor and this is not possible with the Trusty Shield.

Also realize that with no equipment the distribution looks exactly the same as the Trusty Shield except translate the table 1 column to the left (since it's just adding 1 to blocks).

I gotta say after all this analysis I'm thinking 3 gold is a better price.

If we were to compare the average # of defenses by dice count between the King's Guard Armor and Battle Armor, we would see that Battle Armor is strictly better until about 15 dice! After this they remain extremely close out to infinity. In fact, even Royal Shield produces a lower average until 9 dice (but then shoots way ahead after this).

It would seem that the King's Guard Armor is somewhere between the Trusty Shield and Battle Armor. It also seems that Battle Armor is much better than I previously gave it credit for. Of course here Battle Armor was only judged based on average defenses and it certainly has a negative impact to # of attacks as well.

**I've said this in another thread: 1 die has an impact to average # attacks of 0.6 and average # of blocks of 0.2.** So the Battle Armor, on average, nets out -0.6 attack and 2-0.2=1.8 block. This is probably the best way to value items that add or subtract dice.

Bastard Sword then gives 1.6 attack and 0.2 block.

The Reaper's Trident gives 3-0.6*2=1.8 attack and -0.2*2=-0.4 block. etc. Interestingly, the impact to your averages of this card is nearly identical to a card that says "Gain +3 dice and lose 1 shield if you have any" because 3 dice is 0.6*3=1.8 attack and 0.2*3=0.6 block... so to get 0.6 block to -0.4 block you subtract 1 shield.

All things considered, I think the King's Guard Armor is closer to a 3 gold item than a 2.