I am an old (50) but advancing rider, trying to decide if Seventh Secret at Mt. Fromme is within my ability level. Also curious about Severed D.
I've ridden Angry M, Rupert, and Pangor,which were fine. I've ridden all of the Whistler blacks, except Original Sin. 'Line of control' kicked my ass because it was so narrow, but otherwise these trails are enjoyable. Sometimes they're very challenging and I'll pass on the hardest lines, but otherwise 80-90% within my comfort zone.
By and large, I like the jank, and I really like exploring new trails. I just want to stay safe when I do.
I think you'll be fine. More rock armoring on 7th - think the exit turn at the bottom of Angry for comparison to some of the corners on 7th.
Severed is pretty fall line and there is one section with a couple of drops - just after the intersection with Penny Lane climb trail. There is a ride around so just be aware and don't launch off unexpectedly.
Severed is a lot more difficult than 7th. As long as you can commit to the (sometimes tricky) turns, 7th has really nice flow (save for a couple of not really optional, but low skinnies) and is one of the few trails on the NS that is truly wet weather friendly. I have ridden it (mostly) in 2 different thunder and hail storms and 1 "normal" rain storm. (I really need to ride it dry so I can be relaxed enough to clean all the corners...)
Oh and if you like jank, there is a lot to choose from, especially the Old Skool trails, many of which may not be, ah, on all the map(s), like Janet's Granite. Executioner, Upper Oil Can, Boogieman, Lady's Only, Pipeline (wood features galore); Grannies, Bookwus... And hey, if you want a classic Shore experience lower down, just ride BP back to the road - I won't do it - it freaks me out - too exposed. Seymour & Cypress both have jank a-plenty. So do Burke (Upper Elevator, Deliverance, Upper Vic's) and Eagle Mtn., too.