The eyes can be called a circuit that opens up in the brain and eyes to allow the user to “perceive death”, “the conceptual death of an existence”, as visual signals in the form of lines of death and points of death.

The ability to perceive death of a being or object depends entirely upon the user’s perception of death.  Rather than “seeing”, it is more like they are observing everything at a higher level. “Death" is invisible to normal people, only accessed through perceiving the natural flaws with overly strong spiritual sight by looking through channels that normal people cannot perceive. In perceiving death it can be said they see the Root of existence itself. They are similar to the eyes possessed by the Celtic God, Balor, which were able to actualize death simply by looking and they have not been possessed by anyone else since then.

Rogue Level	Feature
3rd	Mystic eyes activation, Lines of Death
9th	Arcane Lines
13th	Lines of Death improved
17th	Points of Death

Lines of Death

Death emerges to the surface of an existence as lines and cutting along them will result in “Death”. They have no particular structure, so they can be described as solid, black “zigzagging scribbles” all over the world that look like cracks. They can be traced with any sort of object, effectively “breaking” the object along the line, cleanly cutting it without any need for force.

Starting at 3rd level your character opens up these magical circuits causing your characters to see these lines for 1 minute(number of uses is equal to your wisdom modifier per short rest). As a bonus action you activate your eyes and become more aware of the lines. You gain 30 feet Truesight and you can see the lines of death. They show the death of things, the weak points where everything is most easily broken and imperfection in everything that will break down one day. When you attack a creature, you can break their armor and reduce the target’s AC equal to your Wisdom modifier (can only be applied once on a creature). You now deal double damage to inanimate objects without damaging your weapon.

Arcane Lines

Your use of the mystic eyes lets you see the lines of death on magical effects and "kill" them

 Starting at level 9, while your mystic eyes are active, you begin to see lines on magical effects. This allows your to attacks to be considered magical to ignore immunities to physical attacks.

You can now use your reaction to cancel an incoming magic spell or end a magical effect that you can see. Roll a D20+ DEX modifier against the spell DC=10+spell level

Lines of Death Improved

The lines of living organisms will keep changing position as long as it is alive. you  begin to anticipate these lines and will be able to cut them.

Starting at 13th level, while your eyes are activated, you can now add your sneak attack bonus to damage to your target even without anyone flanking them.

Points of Death

 At 17th  level, you now see points of death. Points of death are from where all lines seem to flow, resembling blood vessels. There can be a number of them on an object and whereas the lines are “where things die easily”, the points are “death itself”. The eyes do not actually kill “the body”, as the power of killing someone is very common in the world. The points seen by the eyes end the very meaning of “the existence” of whatever is killed. The destruction and the extinguishing of life that life comes afterward, is only a side effect of destroying their existence.

 Upon landing a critical hit, and while your mystic eyes are active, you force your target to roll a constitution saving throw DC 8+your Dex modifier+ Wisdom modifier. If the target fails, their HP instantly falls to 0. If they succeed, they take the critical damage.