I used to play some 6th and all I have to say is that infantry (most if not all) was weak when compared to cavalry units.
Therefore, if you are going for the aforementioned edition I say they're useless. All they have is a lackluster 5+ AS and fear. No wow for a Rare tier unit.
If you're going to play 6th I suggest you field RBTs, full Silverhelms core/sometimes archers and Dragon Princes with a mage/archmage and some eagles for redirection purposes.
This might be just me, but 6th felt unjust for the Asur due to overpriced units and their overall frailty (White Lions used to have light armor -> 6+ AS in close combat, and no ward for PG's for example). In 7th they're good, but not as amazing as Swordmasters.
Say, why don't you try playing 8th? I find it way less tedious compared to previous editions. You get supporting attacks, which make infantry far more useful, random charge distance, which prevents lurking for those perfect winning charges. I remember the horror of going 1 inch forward for like 2 or 3 turns just to get that one charge and then lose the game because you failed it by 1-2 inches.
However, if you're certain you won't be playing 7th/8th/Kings of War and still want to sell your Phoenix Guard, I'm willing to buy them (if the're metal that is)
