I played through NG+14 (including the DLCs) and the most effective weapons I've found were/are:
I wonder what the best weapons are at super high levels (and NG+n) after all the recent changes?
Months and months ago I came to the conclusion of Anri's Straight Sword thanks to the crazy LCK scaling on top of STR and DEX. That thing can have close to 500 AR before any buffs with the ultra fast and versatile moveset of a straight sword. I tried a lot of different weapons and builds but nothing seemed to come even close at the time.
1. Anri's pre-change w/ high luck + 99 hollowing + Hollow infused max whatever in offhand + carthus rouge.
2. Sunlight Straight Sword current.
3. Millwood Battle Axe.
4. Anri's now.
When doing most of those NG+ runs (for Slabs), I used #1 and breezed through every boss. Yeah, I can do nearly 800dmg with my +5 Dragonslayer Greataxe in one swing, but why bother when I can do 1000+dmg with two swings of a SS/BA in less time, using less stamina?
I have crazy stats btw, like everything is at 60 except vig/end/att and Luck because I respec'd out of it.
Heavy and Ultra weapons suck for high NG+'s, too slow, too much stamina usage, not enough stagger power, the only "plus" is the ability to continue your attack through an enemy's weakest one so you still take damage (which is almost always >40% of your health).