I think the early Hammer was a big drag - Stewardess does almost the same thing, and leaves a body behind (it’s fine for breaking Graveyards and Jails, but I don’t have any early buildings it can break on its own, and 3 gold + card for 3 hasty damage to a building is very inefficient) - that would have opened you up to tech something else on turn 2 (maybe that Elite Training you were looking at, or just a Gunpoint Taxman who is pretty good at applying pressure and hedging against Nullcraft).
I think the whole max Oni / Origin Story dance was a wash on either side. I respect the possibility by using a tech slot on Origin Story, you respect Origin Story by not teching Art of War (although if I get cheeky and skip the OS, or just draw poorly, then chaining Art of War will kill me 100%, so it’s a plausible gambit). After that, we’re trading mostly even on gold if you do max out Oni, or I just don’t play the Story if you don’t, and we’re still mostly even.
My big advantage came from being able to leverage the extra gold as P2 to get a Battle Suits into play, which let all my 0 and 1 cost guys trade up.
I think your Turn 1 comment was correct - leverage Zane to make good trades. I didn’t do very much of that, just trading 4 gold for your 3 gold & 2 cards, but making even trades and leveraging the extra worker is basic Player 2 strategy. You never summoned Zane at all? The threat was pretty constraining, though.