Depends on the requirements of the team, to be honest.
While physical Aegislash has an edge over special, the latter is still fine if your team needs a special tank. **The IVs in both defences will come into play while attacking, so that's something you want to check as well.**
Initially I'd swear by a physical Shadow Sneak+Kings Shield+ (SD or attacking moves), but after using a special Aegislash to great effect, I found a Sub+Kings Shield+Flash Cannon+ Shadow Ball worked fine as well, against lower tiers. Obviously if you're running against Ubers (which I assume isn't the case), then it's not very good, but for online battles it can stall unprepared teams till kingdom come (with leftovers).
Going the special route means forgoing Gyro Ball and Shadow Sneak, but if neither of those are an issue, then Flash Cannon and Shadow Ball are great moves. Since one slot is definitely fixed for Kings Shield, you only have to worry about whether you prefer Sub or Toxic or Shadow Sneak (useful for revenge killing a fast mon that survived with red health) for the other slot.
To summarise, the only real issue I see with using a special movepool is losing access to Gyro Ball and/or Shadow Sneak. If Sacred Sword is a must for your set, then the cons outweigh the pros, so you can have Swords Dance/Kings Shield/Shadow Sneak/Sacred Sword.
Before all this, though, **check your defence IVs, those are the most important here!!**