Pyroar, Aegislash's worst enemy!
Woah such a tough question. Sometimes I like to use Swords Dance one or two times and begin sweeping with Shadow Sneak, and annoy physical attackers with King's Shield (ha, suck it Blaziken, 2 attack decreases for you). But there are those times when you're up against a Pokemon that resists fighting-type moves and you can't set up against, so shadow claw could be useful in those situations.
It's honestly down to preference, I would choose Shadow Sneak myself. Or if you don't set up that often, you could replace Swords Dance with Shadow Claw so you can have both!
I would either choose Shadow Sneak or replace Swords Dance/Sacred Sword with Shadow Claw and keep both Ghost-type moves. I would choose the former if I were you, I only provided you with the latter if you felt you didn't use Swords Dance often enough.