I personally do not like the idea that weapons should be the same/similar for PvP and PvE. For example the Mythoclast. The mythoclast is currently the hardest gun to earn in the game and should be recognized for it. Only the strongest guardians stand before Atheon on hard and of those guardians even fewer are rewarded the mythoclast. However, the weapon was too effective in PvP and was heavily nerfed not only in PvP but in PvE as well and that brought along a lot of complaints from the community. Bungie said they were going to find a balanced ground in between PvP and PvE. The mythoclast would be pretty balanced IMO if they returned it to normal but took away precision damage in PvP.
Another example is shotguns in destiny. Many of destiny's shotguns are very powerful in PvP and can have too much range when the shotgun is upgraded to do so. But on the other hand, shotguns are almost never used in PvE. Not because shotguns are bad but because they cant compete with most snipers and fusion rifles. Shotguns are honestly too weak in PvE and need some sort of re-balancing such as increasing their range dramatically.
What other guns do you think should be different in PvP and PvE? Also, is it because the weapon is too strong or too weak?