In Pet Database, Unknown Soldier’s Living Shadow has 3 weapon pool skills, but after actual testing, it was found that they cannot use these weapon pool skills correctly in actual games, they only use general attacks.
I think this is a serious bug, especially with the addition of damage reducting effect for Living Shadow in the current beta version. If they can use weapon pool skills correctly, they can not only stack more bleeding damage, but also cover the damage reducting effect for more enemies. But due to a bug, the damage reduction effect of Living Shadow can only be given to one enemy now.
I don’t recommend digging through the game data then. You will find all sorts of things the game is “supposed to do”, but was either cut or unused, or simply did not work and was abandoned.
These WPS were added long ago to randomize the living shadow’s animations, but ultimately the pet needed a weapon attack to scale with the player’s damage, which does not work with WPS, so they are, as you say, non-functional.