Now that DCs can cap you, Steelshells will take you to the cap for around 80-83. For WAR scythe, that's the 281-299 range. For staff, 275-293. For club, 265-283.
Personally, I had everything capped on my WAR for 75 before the cap raised, and all WSs unlocked that WAR could unlock. For getting past the 75 caps (which isn't really necessary if you're just after blue proc WSs, aside from extra accuracy), so far I've done a mix of abyssea and non-abyssea skillups. If Seaboard Vultures are kicking your ***, you might wanna look into why that is. Is your DNC sub fully leveled? Curing Waltz III is very important, after all. I use a bit of PDT gear for soloing them, but I don't have a particularly high amount of it, I don't think. What I've been using is:
Replace the weapons for whatever you're skilling, of course. For grip, I use either Pole Grip or Uther's Trip, since I don't have an Eisen Grip. Before getting Twilight Torque, I used Evasion Torque. I'm trying to get a Grim Cuirass, but I've also considered Versa Hauberk +1 since it's cheaper. The Dark Ring has PDT-3% since I haven't managed to get a better one yet (before getting this one I used a Patronus Ring). The ASA pants have PDT-4%. I also have capped evasion, with 4 merits in it. Parrying is 254 (without gear) currently.
With that setup, the birds haven't been too hard (especially with staff, since you can use Earth/Terra's Staff for an extra PDT-20%). I saw someone mentioned Orichalcumshells, but if Seaboard Vultures are tearing through you, then Orichalcumshells will rape you and kick you out the door without cab fare. :P
But yeah, as someone mentioned, Zvahl Fortalices will take you to the 75 cap for your skill. That's 256 scythe, 250 staff, and 240 club.