Raage had several rounds of trials at United, but after being offered terms by the Gunners in March, he did not hesitate to accept.
The former Brommapojkarna attacker told fotbolltransfers.com: "It is something everyone wants, you do not turn down something like this, it's good for my development.
"I started training with United in 2010 and it continued until 2012. I was there six or seven times. I do not know why it did not come to anything, it was my agent who took care of that part. All I know is that it went well for me when I trained with them."
Asked what Gunners fans can expect, Raage joked: "I'm a bit like Arjen Robben actually!
"I am left footed and pretty much like to cut in and shoot. But it's hard to describe himself, the crowd gets to do that instead."
- thanks to fotbolltransfers.com