I tried doing it before I reached rank 10, maybe I just didn't play safe enough, but I could barely survive the first 2-3 Bloodrages.
I know Weaken isn't stackable (although I have heard back in the day, that multiple Necro's could stack the effect of Weaken), but there's other non stackables that doesn't do this, Darkblood's Shocked and Thunderstruck, all of Chaos Slayer's debuffs (I'm pretty sure, haven't used it in ages), Archpaladin's Righteous Seal, Arachno's Cocoon, VoT's Super Taster and Sun. I was just mentioning debuffs that work similarly to Necro's Weaken, there's also all the different non stackable, loopable DoTs, ally buffs and other weird effects, so why would Weaken need to do this? I know Ranger's Scorching Arrow and Stonecrusher's Resonance (only resonance, not Dissonance) also does this, but those are the only other examples I can think of though.
In any case, Necro is a good class, it does above average damage, can solo pretty well, it can solo Maximum Slugfit for the most part and if the enemy doesn't to tons of damage to you, it's possible to spam every skill that isn't Summon Undead, you just need to be slightly wary of the extra damage from Infect while in Deadly Frenzy. It's definitely back on my list of recommended classes, especially since you need Doomwood rep for Blaze Binder anyways and after that, it's just about getting to the top of the Necrotower and get a 5% drop from Creature Creation.
Deadly Frenzy only seems to increase the damage by about 2.3 times though.
Edit: apparently my suspicion was right, it's the rank 4 passive that makes Deadly Frenzy seem weaker than it actually is, because of the way they stack together, oh well..
< Message edited by Metakirby -- 6/19/2017 6:42:27 >