Seal of the Blessed Champion: A holy seal of heavenly omnipotence, given to aid mortal warriors in their fight against chaos and darkness.
Although this is the top tiered seal, sometimes the T5 “Z Seal” is used instead, due to a slightly cheaper mana cost, and same duration / length as T6. However, with the T6 Seal, you are paying an extra 5 mana for only a higher hp buff, meaning it has a less efficient damage / heal buff to mana cost ratio compared to the T5 Holy Warrior. Also, this is a rare T6 ability that does not grant the user an extra 2 Wisdom, meaning the seal does not increase the duration or range of the buffs any more than the tier 5 seal. So if you are looking for the most efficient way to permanently keep a buff going as paladin, use T5 seal, not T6.
TL:DR - T5 seal is cheaper but has almost the same effect, T6 only increases HP
Descriptions in-game are currently bugged, causing wis-affecting equipment to appear to have twice the effect they really do (this effect is only for the descriptions- not the actual result). This page shows the actual formulas, not the ones based off the (incorrect) descriptions.