The Icelandic goalkeeper joined the club on Monday, and will battle with Bernd Leno for the No 1 spot.
“I would say I'm a modern goalkeeper," Runarsson told Arsenal.com. “It is one of my best attributes that I'm comfortable with my feet, I can play with my right and left foot, I am not afraid to play as a sweeper and I am good one against one.
“For goalkeepers, because we play a position where if we make a mistake, most of the time it will lead to [a goal] so you need to have a strong mindset.
“You need to have a mindset where you demand the best so you don't make those mistakes too often. That's why you need to work hard, you need to train hard to be able to perform in the matches."
Arteta said of their new No13: “We want to create healthy competition for places and we look forward to seeing Alex bring further depth to the goalkeeping position."