-Current behaviour: Some magical helmets are described as to not give defense agaisnt critical hits. I do not know if they actually give this defense and simply lack this description.
-Expected behaviour: These helmets should confer a resistance against critical hits and this should be in the item description.
I am sorry if this has been adressed previously - I couldnt find it.
Some helmets, namlely Dragon Helm and Helm of the Rock are not displayed as "protects against critical hits" (there may be others as well).
Now, for some head gear this makes sense, such as Bronze Ioun Stone. But it seems weird that solid helms such as the Dragon helm and Helm of the Rock does not protect against critical hits. If there is some sort of balance reason behind this, it doesnt make sense in my opinion, they should rahter have lower bonuses.
I have not tested whether they actually *do* protect agaisnt crit. hits and simply lack the description, but since this is not listed this has prevented me from using dragon helm for instance.
If they do not protect agaisnt critical hits I believe they should. They look and are described as at least as protective as a normal helmet. It would be weird if a helmet created by solid dragon scales does not confer at least the same defense as a normal Iron helmet.