Attacks doing 0 damage

Hey guys. Still relatively new to this so not sure if there's some weird mechanic I'm overlooking here. I attacked a guy for my mission and was regularly hitting him, but doing 0 damage. In the meantime he casually whittled away at my health until I died. Anyone know what's up with this? I used different weapons, got lots of hits but 0 damage and he's wearing no armour.



http://i.imgur.com/fEksdvj.png



Thanks in advance!

This means their defence is higher than your strength - you generally won't be able to hit them, without using temporary weapons and/or asking others to join in on the attack (which will reduce your target's stats, which should in turn allow you to hit)