rift quest:Augmenting Wardstones  

Waves of Madness World Event Rift: Patch 1.3

You CAN bless a wardstone that is already at max level. It updates the quest, it just does not improve the wardstone.

If you do not yet have the Ascended Power: Bless Wardstone ability, you receive the quest Blessing Wardstones instead. Go speak to Garad Nallam in Meridian and buy Ascended Power: Bless Wardstone for 50 Planarite.

After you return to the Runeguard quest giver you will be given Augmenting Wardstones.