It has been my bad experience that the Arena and the Dungeon are two different games. A large number of skills, proc and affixes used in the Dungeon do not work in the Arena.
It's kind of hit or miss, what does or doesn't work in the Arena. You just gotta try them out to find out. Just saying, so newbies don't get disappointed like I was.
Another issue with the Arena. You BETTER have a reliable high speed connection, along with a reliable dedicated device. Just imagine a text msg, phone call, or other notifications trying to get through during the time in the Arena.