I am running Curse of Strahd for my gaming group and am trying to put general shapes on future encounters and occurrences. I thought it would be cool if, when Strahd uses his Lair Action to create a Shadow from one of the PCs, that it would somehow be slightly better than a normal Shadow because it still has some (minuscule) connection to an intelligent living creature. Especially since the PC in question was never killed in order for the Shadow to come about.
My initial thoughts were to make a Shadow created in this way more intelligent and cunning than the base Shadow and to possibly have it retain an ability from the PC it was created off of. This would give my PCs a new minor antagonistic force to deal with that still holds relevance and appeal in destroying.
Would adding this house rule cause balance issues?