I'm fairly new to Blender (and modeling in general), and I have an issue that occurs when trying to join two objects! I'm trying to attach a weapon to the hand of a human, but when I do so, the lighting for either object messes up completely! I've done this before with similar models without this issue ever happening, so I can't figure out why it does so in this case! I would really appreciate it if I could get some help on this matter! :)
Lemon and Aoradon, you solved my problem! It appears it was the mirror transform I had used that somehow caused this problem to occur! Flipping it back and applying all modifiers/scales/etc. before copying it in and joining it with the other mesh, completely solved my issue!
Thank you guys very much :)