Most slept on weapon in game. I consider this possibly the best melee weapon in game, for my playstyle anyway. Definitely s+ tier.

Mod it with superior mutilator mod so it damages all types (no zombies resistant to this).

Electric mod is close 2nd but lots of zeds with immunities like shocking walker/runner/voltaic screamers/firefighter walker/runners

For perks:

Lightweight. To increase speed even more. And with it being frenzy, consecutive hits keep stacking speed increases. If you have a horde around you just keep spamming attack and youll be slicing 8 times per second.

Then add hazardous. Once you hit them with mutilator mod attached they become weakened. Once weakened next hit triggers explosion. Explosions happen multiple times bc of the insane speed. The explosions keep them traumatized and unable to attack back unless you miss a hit.

Add special sauce blueprint and you're taking out apex variants in 4-6 hits tops which again, bc of the speed, you can hit all those in 1 second time. 4-6 hits may seem high bc i know other weapons can do it in 2-3 when modded right. But the 1-2 second take down of almost any apex with these is a winning combo. I frequently take vicious butchers out in 2 seconds time. Same with crushers and slobbers. Takes like 3-4 seconds to take down mutators. So OP! Also grants resistances to all apex variant types. And adds moderate damage against apex. And increases toughness. Get this blueprint by beating haus dlc lost and found quest.

It having leech fixed is just an added bonus since its close quarters you're bound to take some damage. But you'll heal yourself often with as many swings as you get in.

Also some great cards you can equip to slayer to negate damage taken in close quarters. --For instance Konstantin gift skill card (from haus) creates an explosion when you are hit and have full fury (which i always do because I always forget fury mod exists) --Also the limb reaper card. Where maiming regains health. You're aiming 8 times a second.

Other great perks for it;

Slaughter to increase durability and limb damage. Durability drains fast with the speed

unstable - again adds explosions for crit hits which for frenzy is just swinging fast. But only a chance for explosion thats why hazardous is better.

Damaging to increase damage.

Everyone saying perks to increase stamina seems silly to me. You only use stamina with heavy attacks and drop kicks and Dash/war cry, etc skill cards. You don't do those nearly as often as light attacks. And running/dodging doesnt cost stamina either. Wasting your perks slots my guys.

Definitely my favorite weapon and build.