I began playing it again today, and just now defeated Tower Knight. What concerns me is that I only did, at the most, 8 Damage to him. And I was in base Soldier gear, except for a Heater Shield, and a Bastard Sword that I had to two-hand (which is what was dishing out 8 damage on a strike).
After some initial panicking and running around to avoid archer fire, I tried to retreat from Tower Knight and saw that I could actually eliminate the archers. After doing so, and clearing out the rest that fell off and landed near Tower Knight, it was just me and the big guy.
The fight played out similar to beating Asylum Demon to death with your fists on an NG in Dark Souls, except for the fact that I could heal; I couldn't take more than a few hits from him, and I had to keep attacking him while evading his attacks for about 10 minutes or so, maybe. I did succeed however, but due to how long it took me to take down Tower Knight, I'm curious as to whether or not I should have been anywhere near him yet.
I'd only just beaten Phalanx and levelled up a bit before continuing through the level, and I didn't die the whole way through to Tower Knight, so I wasn't expecting any kind of boss battle that tough to face. My exact stats were:
14 Vitality
9 Intelligence
15 Endurance
15 Strength
12 Dexterity
8 Magic
10 Faith
10 Luck
I have had over 350 hours of experience in Dark Souls prior to this, so I'm very well acquainted with the combat and such.