Okay, so I just finished replaying all chapters with an average intensity of 6.9 and all treasure chests collected. Some later chapters on 7.0-9.0 are intense as hell, it's incredible. My file says 97.8%, so I'm guessing the remaining 100 or so treasure hunt achievements I have left and maybe the few power-ups I haven't obtained yet are the remaining 2.2%.
Since this thread could use a bit more activity, I wanna know what your best/most useful weapons are so far.
I've got a collection of a ton of pretty damn good weapons, though I only use three of them. Others have a lot of potential too, but usually fail in one category, like one weapon having great abilities but almost no attack power.
1.
Darkness Bow
Ranged: 6*
Melee: None
Value: 245
Abilities:
Side-dash ch. shot +3
In-peril autododge +3
I actually got extremely lucky and got this one from replaying the first chapter on 9.0 a few times. One forward-dash charged shot with it killed just about every enemy throughout the rest of the game, especially combined with Energy Charge Lvl4. Obviously abused the hell out of it for the rest of the story. 
2.
Insight Staff
Ranged: 4*
Melee: None
Value: 333
Abilities:
Overall Defense +6
Petrification +4
Speed +3
Forward-dash ch. shot +2
Forward-dash cont. fire +1
In-peril attack boost +1
Got this one as a random weapon online (lucky as hell lol) and it's my main weapon for high intensity runs because it's near impossible to survive without at least a decent defense boost on your weapon. It's really great online as well.
3.
Raptor Claws
Ranged: 4*
Melee: 4*
Value: 273
Abilities:
Overall Defense +3
Speed +3
Awesome, balanced claws that I mostly use for speedruns. Claws are fast naturally but with a speed modifier your running speed is just insane. Pretty funny to use online too, just running around like a madman and occasionally doing a melee dash attack into unsuspecting victims.