Honestly just sounds like you died to it a few times in PvP and wrote this. You just never mention how sentinel shield generates a larger area of cover when blocking, gives a damage buff and has a long range ability to throw a shield that 1 hits any non-super and chains with near aimbot/perfect accuracy towards someone else multiple times. CHAINED with controller demolition which procs with the shield. Also Sentinel Shield lasts longer and uses less energy per ability compared to Arc Staff, as well comparing Arc Staff with actual exotics VS no exotic sentinel shield is kinda unfair. Arc Staff is decently easy to dodge by jumping over a swipe or running away, they cant catch up unless they swipe which uses energy. Each super has pros and cons and only naming the pros of one and the cons of another is petty