Ancestral Arashi Shackles

Over a millenia ago, the Arashi family was enslaved to Orcs.  The family was able to break from their chains to freedom via these shackles. 

Though not named at the time, the families blue and white subspecies of Mirran Tortle gave them natural affinities to magic.  Just like their simic experimented cousins the Mirrar Vedalken, their exceedingly high intellect granted this.  

The families liberation from Orc Slavery came from the sacrifice of their 5 member Elder Council.  They ritual attuned their souls to the slave shackles of Hikaru Arashi, the head of the family and of who's name literally means 'the pioneer' or 'the first'.  The shackles became his arcane focus and dawned the ability Soul Smite.  The ability to unleash raw force energy when applied with unarmed, or other natural means of strikes.  This new found power allowed Hikaru to single handedly free the Arashi Family.  

The Iron Shackles have been passed down generation to generation through the head family, as it's their burden of being the Guardian of the family and never let such an affliction harm their bloodline again.  With each new bearer, there is an understanding of passing to the next life will first require a 5 generation duty to the shackles.  As their soul is added to the shackles, the most elder ex-bearer moves on to the afterlife in peace - as the shackles require 5 souls to power at all times.  

Soul Smite: 
When you hit a creature with either an unarmed melee weapon attack or a fist/foot style weapon melee attack, Soul Smite will deal force damage, in addition to the weapon's damage. 
The extra damage at cantrip level (no cost) increases as you get higher level:  1d6 damage at 1st level, 2d6 damage at 5th level , 3d6 damage at 11th level and 4d6 damage at 17th level. 

*In addition, you can expend one spell slot at [Spell Slot Level x 1d6] to add to the base Soul Smite Damage to a maximum of [(Proficiency Bonus x 1d6) + 1 if inspiration is charged]

The bearer can only permanently lock the shackles on their wrists.  If somehow removed, the bearer gains 1 level of exhaustion every 1 hour till death or until shackles are re-equipped and exhaustion dissipates. 

Only Arashi/Mirran Tortle bloodlines are blood attuned to use Ancestral Shackles.  If any others wear Ancestral Shackles, no effect takes place and the ex-bearer souls are released after 7 days.