*WARNING* WALL OF TEXT AHEAD
Yeah, Bloodbrides should be more skilled than wyches, there's a couple of different fixes GW could do. They are better equipped than basic wyches, They are more skilled, They are more experienced, Thus they should be more killy and or harder to hit. Here's a list of possibilities I just brain stormed, yes some are bad, some are too good, I just want to put them out there:
On the topic of Wych Cult as a whole, I guess we'd have to take balance into account. Kabals are our shooty, anti-elite/high toughness group. Coven are our Tough-moderate killy group, so what are Wych cult? The way I see it, I think they should be the fast moving, hard hitting, glass cannons that either kill or be killed. If you manage to tie-down the reavers, they deserve to die. Gotta go fast. Maybe something of a buff like, they move shoot and then finish their move in the same direction. Although at that point you might as well just give them back their "fly over, but still hit" ability that they used to have.
So from my perspective, Wych Cult should be a close quarters glass cannon across the board, with great speed or transports being their way of surviving. We already have the transports/DS stratagem, Hellions have good movement and Reavers are even faster than that. So movement is covered. with the lack of armor and toughness (other than reavers) the glass aspect is covered. The problem is, they don't hit hard enough. we're more of a pea-shooter than an actual cannon. I don't think Wych cult should deal with Vehicles, leave that to the Dark Lances. So that leaves Elites, Troops and Hordes to deal with. I like the idea of reavers being the anti-elite option. zoom in, blast em, charge if needed to mop-up or try to stay safe. If anything, I feel like they should get more shots (2 instead of 1) on assault weapons. That way it'll encourage you to advance more often and still get 1 hit (4+ BS on advance) rather than whiffing that single shot in your 3 man squad. Or just make the weapons cheaper.
Hellions are interesting because they're one of our very few options of causing flat 2 damage on their weapons, whether this is because of how large the blades on their weapons are or because they are intended to be moving fast as they swing is beyond me. So they fulfill the role massed attacks. Problem is, Their attacks are a weird hybrid of lots of attacks, low AP and good damage.
Ranged: 2 Shots, 3+ BS, 4+ poison. No AP. They wound Space Marines the same as Kabalites but pay for 2.5x the price and cant go in transports. (Tantalus is still fair game tho, lol.)
Melee: 2 Attacks, 3+ WS, S4, No AP, 2 dmg.
Each Hellion with shooting and charging before T3, kill 4/9 of a Space Marine, for 17pts that's abysmal. No cannon here, not even a hammer. Before drugs, you're paying 38.25 pts per wound. Problem is, Same goes for Wyches. before drugs its 38.57 pts per wound. Even 13 pt Space Marines return wounds to Wyches at ~20.65 pts per wound (Overwatch included). Against something like guardsmen with 5+ armor, its 16.4 pts per wound for hellions and 15 per wych. And that's to kill a 3-5 pt enemy. So I guess something like a succubus or Hekatrix can run with the squad and greatly boost the damage potential against armored opponents, but once again, this potential is wasted against horde types. So basically, I think that Hellions and Wyches should be changed to fill a role. I personally say keep Wyches as they are, maybe a small buff or points decrease to make them more efficient tarpits, and Hellions should be made to be more anti-horde.
So to summarize everything I just said,
-Reavers are the anti-elite, I like that, just need cheaper weapons to be useful/point efficient.
-Succbus is the best wych cult anti armor for troops.
-Wyches and Hellions are neither good against troops nor Horde and essentially serve no purpose other than mobile tarpits. Which only Wyches are ok at. It's an incredibly inefficient points dump. So to fill the niche that the army actually needs across the board, make wyches cheaper to make a more efficient tarpit, and make Hellions the anti horde option somehow, whether it's a HoW per 10 models in enemy unit, a -1 AP on their CC attacks, Double unit losses from Morale, Just do something!