Here is a Drawing I did Last Year, of One of Nightmare Moon's Guards.

Personally, I think Every Royal Guard in MLP (Even Celestia's,) should have Beaked Helmets. When you think about it, it can Protect their Faces from Damage. Too bad in The Show they have Helmets with Visible Faces, open for attack. Every Royal Guard in My MLP Fanfiction, will have a Beaked Helmet Though.

Someday, I'll do a Celestia Royal Guard with a Beaked Helmet like This one.