Op.10 no.2 is extremely difficult. To the less experienced pianist it sounds fairly easy, but to play that chromatic scale, legatissimo, with the 3rd, 4th and 5th at that speed... so hard! If you're around Grade 5 level I wouldn't bother going anywhere near this. It's probably the hardest Chopin etude, and they are all very hard...
Oh, and by the way - you are arm shouldn't be aching, that indicates incorrect technique. Practising Op.10 no.2 your fingers will ache a lot at first, it is definitely recommended to stop playing and don't push it too hard
Since starting Music at University my playing has come on leaps and bounds, through a lot of hard work, 2-3 hours of practice a day. I just finished learning Rachmaninoff's Prelude in G Minor (Op.23 no.5), Chopin Nocturne in B (Op.9 No.3) and C minor (Op.posth). The Rachmaninoff was quite a stretch technically for me and the Nocturne in B was also pretty difficult, C minor was easy though. Got given Shostakovich's 24 Preludes and Fugues for Christmas and have been working through a few of them now - good practice for sight reading although some of them are really difficult. Was also given Beethoven's piano sonatas, have had a cursory glance at Op.2 no.1 so far.