You need a ton of damage and sustain. If you do enough danage, the rounds will get shorter and so much easier. If you don't have enough sustain, you will run out if resources and will most definitely die. If you are having troubles with sustain I recommend using tripots and engine guardian. Furthermore, you need to get really good at dodging and the most important thing is that you NEED to learn the mechanics of the arenas. The first time may take you 4 hours of dying, but everytime you die you learn something new and you'll get better at the arena. So remember to not give up and just repeat and repeat till you know how every single arena round works.

Thanks guys. I found it was easy in normal cos of fast kills, not that it's too hard but I get it.