As mentioned earlier, this is almost always due to the save file being marked as by your operating system. Unchecking this property in the file's properties menu will resolve it.
Yes. Diablo 2 (via Lutris or Battle.net on Steam Deck) stores saves in a compatibility layer folder. Find the Save directory and copy the file there. Proton versions may affect location. diablo 2 paladin save file link
: Paladin skills (Combat, Offensive Auras, Defensive Auras) are encoded in a variable-length section identified by the "if" (0x69 0x66) signature. Where to Find and Use Paladin Save Files As mentioned earlier, this is almost always due
Using third-party save files comes with minor risks that are easy to mitigate. As mentioned earlier