A Weakgeek said:
Few issues lad. Mail was very hard to pierce, which is why it was used from 300 bc to even now in the form of shark protection. If mail was easy to pierce, it wouldn't have been the go to armor for centuries.
Full plate armor weighs only 60-80 lbs, with the armor on the arms and legs thinner and the entire suit designed to fit the individual. With a bit of time to get used to it, the armor all but disappears on you (I know from experience with my chainmail). The helmet is all that restricts your breathing a bit (plus your vision and hearing).