I have to admit that this game was far more challenging than the first one. Also, did anyone unlock Kanako? She doesn't seem to appear anywhere.
Yeah, no Kanako either.
But to be honest, I find this game to be easier than the previous one. Mainly because of the reduced damage and HP.
Just upgrade your armor to increase your defense up to 300(it's easy) and you'll be nigh-invincible, no-selling everything but the attacks from the final boss and the bonus bosses.
I use Byakuren to further emphasize it. "Superhuman passing through~"
As for weapons, I think the unique ones is way easier to get than in the previous game and you'll get to use them more than normal weapons. The only downside is lower stats, but the options it gives you more than pays for that.
For your partner, best weapon without a doubt is Sakuya's knifes. They're good at aiming them and can trigger the special attack almost every time.
As for you, that varies.
For bosses, Roukanken and Hakurouken is good because other than being a twin sword, its special attack grants invincibility(and it looks like I'm using Byakuren's SC in HM).
For mobs, Suika's horns with its spin attack, that sucks enemies in, is great to soak a lot of damage while keeping yourself mobile. Also works fine on bosses too, if you know when to dodge.
Once you got these weapons, just breeze through the game while keeping them upgraded to match the enemies' strength.
But now, with a level 495 Laevanteinn, I just wipe everything that comes close. It works like the Sword of Hisou(delayed strikes has guard frames). The Four of a Kind special attack is pretty neat too.
In short, it's easier, but it's more fun to play, since you can last longer and going melee actually worth it now.
Hoping for a more challenging quests now. Maybe in some future patches.