But what if you pit 1 Barbarian Troll and 1 Titan against each other under equal conditions? Assuming both heroes have 0 attack and 0 defense, neutral luck and morale, no magic, and the Titan can't one-shot the Barbarian Troll, will the Barbarian Troll heal each turn and slowly chip away at the Titan? Interesting...

And what's so interesting? The Titan moves close to the Troll and calmly defeats him with an attack and a spell (the AI won't be smart enough to skip a turn): in online play, the attacker will have to retreat due to a stalemate, but against the AI, it's a clear victory.
In a simple ranged battle, the Troll simply won't have enough shots to kill the Titan.

And the Archer costs a little more, but it's more expensive: 9150 versus 140. That's the situation.

Yeah, when playing as a Knight, things are definitely not great if you have to spend that much for the second level.