From what i have seen from the game up to level 35, (desperately hoping this changes in higher end dungeons) lancers and dragoons are not allowed to roll on heavy armor... which for questing and dungeon reasons, we obviously prefer it anyway. i regularly see in each and every dungeon that there are 2 heavy armor sets, the ethereal and unique pieces, the unique (green pieces) for the most part all seem to specify all proper tank classes, but the ethereal pieces, which are usually just a little below the quality of the uniques also allow for lancers and dragoons to roll on Wear✔ them. i don't know about the rest of the lancers and dragoons out there, but i've come to the understanding that dexterity does literally nothing for us in terms of dps anyway, so why not take the parry from the heavy armor that's supposed to be available from us and the extra free armor value... and put it towards our survivability...