u can't make a universal armor which gives maximize use for Templar and Knight....
Templar is a Block-based Tank, that mean u need STR and Block success (here i suggest the Holy Commander Armor) also you need STR/Block Gems and i personally will use Evasion Formulas on the Equip.
Knight is an evasion-based Tank, that mean u need AGI and Evasion (here i suggest the lv 60 Agi Armor or the Spirit Chain Armor - which gives a huge boost to evasion) also you will need Agi Plus Gems and naturally the Evasion Formulas.
the Shield is much easier^^ both use the same Shield, the Wall of Redemption.
in the best way... on +6 or 8 with usefull Boni for your Class... and as Templar Str+Block Success Gems and an Evasion Formula, and for the Knight the Agi Plus Gems with Evasion Formula.
If you want to use it for both, you should use the Agi Plus Gems for the Shield with the Evasion Formulas, because your Templar should have a little bit evasion, because every hit which is not blocked (block success works only till 50 %) can dodge if you have enough evasion. So the Evasion Boni would be better for the Templar, than an Block Boni for a Knight.
Armor you should really get 2 Armors... because Templar and Knights don't fit in the needings of Armor.
If you need to choice to 1 Weapon, maybe a Sword with Evasion and full slottet with Agi Plus Gems and Eva Forms....
but thats just my way of thinking :>
hope i could helped you a little.