This is why sean proposed it to be class specified. final evade rate can be put into a thief/archer set's while the block damage+block chance go to ninja/paladin set's OR better yet just put it into the roar of victory buff. given whenever you enter pvp.
I do not know who sean is. Anyways, I don't think it being in a set is a good idea. It takes away from the diversity of builds. I don't understand why having the final evade rate or block rate in sets is a better idea. Having aim/evade relevant again would mean people wouldn't just focus straight for hp and going tank, unless they wanted to. They can go for other viable builds. Having classes you are suggesting such as thief/archer and paladin have a free block rate/ final evade rate with also having stacked hp, just doesn't sound right. People going for evade aim and agi would force people to have less sockets on pure hp and be less tankier. There are so many different builds you could go for.
As I said in my earlier post, for examples :
AGI/AIM/CRIT RATE/CRIT DAMAGE
VIT/CRIT RATE/CRIT DAMAGE/AIM
The possibilities are endless. You could focus on one or two. You could even balance them out. Would you want to be able to miss less vs a ninja who balanced out on AGI/AIM/EVADE? If so, then try to build AIM. If you build more AIM, then you might miss out on other stats that you could have gotten. Would you want that 40% Crit damage socket? Would you want that 40% AIM 20% Evade socket? Or maybe even 40% Evade 20% Aim socket? The choices are plenty. Even if you stack evade, a cap would be implemented.
Would having that extra 40% Evade socket outweight the benefits of having VIT? Your build could already be at the cap final evade rate vs one particular character and their aim could already be capped at missing the % chance it misses at. Having that socket changed out or two of them for VIT could possibly be better since their AIM is low anyways.
But wait, there could also be summoners who stacked AIM, AGI, and VIT. That means they must be very tanky and have high AIM. If you are a Ninja, maybe to be able to have the highest evade vs them, you would need those sockets. Oh wait a minute, if the summoner stacked AIM, AGI, and VIT, that must mean their Crit Rate and Crit Damage must not be capped. Their Crits will not do as much damage.
There are countless scenarios that can alter the playing field.