Mother Sestiss' Armor

Armor (Heavy)

Varies Requires Attunement

In addition to a +3 bonus to AC, this armor bestows no penalty to stealth or dexterity checks. It also grants the benefits of the Haste spell upon its user. Per DnD5e;

Haste

3^rd level transmutation Casting Time: 1 action Range: 30 feet Target: A willing creature that you can see within range Components: V S M (A shaving of licorice root) Duration: Up to 1 minute Classes: Artificer, Sorcerer, Wizard

Choose a willing creature that you can see within range. Until the spell ends, the target’s speed is doubled, it gains a +2 bonus to AC, it has advantage on Dexterity saving throws, and it gains an additional action on each of its turns. That action can be used only to take the Attack (one weapon attack only), Dash, Disengage, Hide, or Use an Object action. When the spell ends, the target can’t move or take actions until after its next turn, as a wave of lethargy sweeps over it.

Mother Sestiss' armor is crafted of mithral and etched with sacred and mystic whorls over its entirety. It also disguises itself as whatever type of clothing the wearer wishes to be seen in; only, it will reveal itself if put to the test in combat, when the whorls begin to glow with a dim, blue light and dispel the illusion of softer garb.

It is an item from another time in human history, before their ken with the elves dissolved into bloodthirsty violence, amidst the Elven Purge. It was commissioned and worn by a fighter sworn to protect this place from Primordial Forces .