These mechanical menaces have a pretty specific grab sequence you'll want to learn - they pause briefly and their chest cavity starts opening which is your cue to dodge roll forward, right as the chamber reaches full extension. The timing's crucial here and you'll want to practice it since getting caught means massive damage. Staying near their right side gives you better positioning, especially when they start their spinning attacks but watch for the blade throws which they love to mix in when you're at medium range.

Pretty interesting detail about their mechanics - they take extra poise damage from lightning attacks, so thunder weapons or spells can help you break their stance faster. The safest approach is baiting their grab attempts, rolling through them and hitting their exposed internals while they're recovering, just make sure you've got at least 35 vigor since surviving a grab gone wrong needs decent health. Using the pillars around the area actually works great for controlling their movement patterns and if you're struggling with both virgins at once spirit summons can keep one busy while you focus down the other.

When they do that spinning blade attack sequence, that's actually one of your best windows to counter especially if you've got a longer reach weapon but don't get greedy since they recover pretty quick and might transition straight into that grab if you're still close.