Shadow of the Iron Tyrant

This is a jagged, palm-sized shard of obsidian-like glass, cold to the touch even in sunlight. It has been inlaid into a leather bracer. When held or worn, it whispers fragmented promises in a language that sounds like cracking ice. It was once part of a seal binding a forgotten shadow-fiend, and it carries a fragment of that entity's will.

Umbral Step

Once per short rest, as a bonus action, you can teleport up to 30 feet to an unoccupied space you can see that is in dim light or darkness. This does not provoke opportunity attacks.

Mark of Sundering

As an action, you can touch a non-magical object or surface and speak the shard's name. The shard imposes a flaw or weakness upon that object—a lock's tumblers seize and rust, a rope becomes brittle, a wooden shield develops a deep crack, or a stone wall gains a hairline fracture. Make a DC 13 ability check using your spellcasting ability or Dexterity (your choice). On a success, the object's structural integrity is compromised; a lock grants advantage to pick it, a rope breaks under 50+ lbs of stress, a shield loses 1 AC until repaired, etc. On a failure, the shard recoils and you take 1d4 psychic damage. Usable proficiency bonus times per long rest.

Drawback — Whispers of Doubt

While worn or held, you have disadvantage on Wisdom (Insight) checks made to discern deception, and you cannot benefit from the Guidance cantrip. The shard's whispers constantly suggest that others are lying to you.