Without the boost, 2h dmg should still be better than 1h pa.

Only the base damage is higher, but 99% of your damage when using PA is style damage, which is why using 2H PA really wasn't worth it before they increased its style damage above a 1H PA. In fact, the poison application of the offhand, plus the offhand damage, and the faster follow up attack made 1H PAs actually out DPS 2H PAs on live in 1.69.

If you were unaware of this, or not making use of this mechanic in 1.69, that's your own fault, and doesn't retroactively change the way that PA functioned 10 years ago.