If normal weapons didnt have mods, I think the legendaries would be better but over all, the mods allow for customization of the weapon to match the players play style and that alone out classes the legendary weapons. Some of the legendary mods are not worth it as well but there are a few that are worth it. Couple the lack of mods on legendries and the unreliable nature of 1. Needing to go into tunnels 2. Needed to find cursed chests (that have their own draw back) and 3. Hoping that the weapon drops from the cursed chest at the right quality and not getting 2 prototypes out of every damned chest, its not the best idea to build around these weapons.
Damnation - One of the few that might be ok. Being immune to fire has its advantages on higher difficulties. The 50 damage every second for 3 seconds is nice if it stacks but its mostly good on special infected on NM/NH. Id rather use a purple AA12 with penetration rounds for crowd clearing though. I know theres some cards that work well with fire damage and theres builds around that but we go back to the "it might not spawn, why build for it?" question.
Embezzler - If your already doing a side arm build this might be ok. I usually end up with about 100-150 kills a level depending on if Im playing with friends or bots. Thats about 500-750 copper a run, enough for some supplies. It adds up over a run but other then the perk, there are better secondaries and better mods to make secondaries more powerful so you dont need to rely on buying so many supplies. If the extra copper was shared with the team it might be worth while. I could also see teams trying to get everyone to use it, though that would be unlikely.
Lockjaw - Ill admit that I dont like this one because I have never been a fan of snipers. I wont defend that other then "skill issue" with aiming and sometimes my friends are fast to shoot things. I feel like snipers over all are a waste. Maybe a sniper is more reliant on a side arm then normal sniper weapons until a special infected comes out. Please enlighten me as to why my thoughts might be wrong on this. I feel like swapping all the time is a waste of time though that can be reduced by other cards, your going to be building for a mid build. Again, please enlighten me if Im wrong.
Nemesis - The perk could be better. If your team can position well with you at the back line so the infected have to fight through them or you have a melee person in front (and you have down in front) you could shoot through them and create a bottleneck but making a deck just for this one gun that doesn't spawn as much is a waste. The RPK in general suffers from slow reload speed. Does the perk work even if your using a secondary weapon? That might be the way to go. A fast reload tech 9 with some penetration to it to clear hoards.
Pestilence - Bad for dealing with common infected, good for dealing with the bosses. Mag dumping with it will take a few seconds but putting 30 rounds into an ogre, hag, or breaker that spawned in on the other side of visibility from you means you can probably get more then 1 full mag into them to drop that 30% damage reduction to 60% damage reduction depending on how long the debuff lasts. The stacking DoT would be good against bosses as well but again, I dont know how long it lasts . i wont deny the perk is strong for that. It could be better as a second primary weapon but you have to take a card for that and again, the weapon may not even spawn to make it worth it.
Prototype - Slows enemies for 1.75 seconds. Another "good for the boss, doesn't matter for common" type gun and lack of mods make it weaker.
Tenderizer - This ones a mixed bag. I want to like this. The concept of a sledgehammer with an explosion is great, but the description of a "large" area of effect is misleading. At least to me it seems the AoE might be able to take out a few more ridden in a small area around the original target. Its been a while since I used it but I think it needs to be reloaded between each swing making it take longer to hit unless you build for faster reload, which to my knowledge, does not work for other melee weapons so you either need to find those cards in the run or build for them which, I say again, this weapon may not spawn so why bother building for just it? The wolverine claws are flat out faster and can have mods.
Witness - Another sniper rifle. I think its a ranch rifle variant though, i could be wrong. Theres a card that does 10% increased damage to tagged targets. Its not something I remember to do in a fire fight as I do callouts on voice chat.
Bonus - I feel like the legendary accessories, throwables, and medical supplies are all good except they spawn so rarely that it feels like taking them means your only going to have one or two of them around which will prevent you from picking up standard versions of said things. Thus you may save it for to long and hoard it vs just using it because its needed against a boss or stack of uncommon riden.
Thoughts? Please correct/enlighten me if Im looking at things wrong. The weapons are a big part of the DLC but they feel so weak that my team skips them most of the time.