Hey there
So i was messing about on my paladin respecing with dualspec one of my specs had this glyph Glyph of Seal of Vengeance - Item - World of Warcraft and when i was that spec i buffed Seal of vengeance then i respeced to my other spec and it lets you keep the expertise even tho you dont have the glyph, so you can use this to have a extra major glyph slot.
Doesnt work in arena since you have to change specs but it works zoning into places so you can go dungeons or raids with this and you can respec in raids so helps you to get max dps by having an extra glyph slot.
Hope this isnt a repost i did search for extra glyph slot and paladin glyphs...