Just to see if my character would have won.
lvl 2 AC 19 +5 1d8+5 Heavy Armor Master for the DR and I have 20 hp
I won 1 out of 5 if I didn't have my clerics buffing me. It was almost 2 out of 5, I got the 1/2 dragon to 1.
I wonder how well you would do without HAM. Also, did you take the +1 AC fighting style?
Not all PCs have that feat, in fact, not all PCs that duel have heavy armor.
I'm kind of curious on this. 7.5 average damage would mean about 7 or so hits on the HD to take him out. That's a lot of rounds. Since he can attack twice per round, I would think that (without HAM) he would only need about 3 or 4 hits (4 rounds max shy of terrible rolls) to take out a PC with about 20 hit points. HAM is pretty powerful.