It’s tough to make a record about weariness without wearing everybody out. Before the Poison, as resigned and lost as anything Marianne Faithfull has done, avoids exhaustion by pairing her with rockers P.J. Harvey and Nick Cave, two rare icons with as much soul mileage as Faithfull herself. Poison is a tribute to Faithfull’s ravaged voice, an instrument with the range and history of a Gregorian chant. Still, her voice can make a mournful party like Blur leader Damon Albarn’s “Last Song” into a celebration of every dark corner of loss. The highlight here is the Harvey song “No Child of Mine” (from Uh Huh Her). Harvey and Faithfull trade verses as if they are teaching the song to each other. Faithfull’s bitter verses are full of what it means to be older, whereas Harvey, in a lovely reversal, reminds Faithfull — in her own distinct, sad way — what it means to be young. In the end, this record is full of sighs, but it’s far from being tired.