The lab was actually pretty big. Full of steel walkways that one can fall off of. Wolverine was able to hold back/knock down SS. Doesn't look like the suit gives him much super strength. He was also slow as sh!t, Ultron def has the speed and strength advantage here. Plus the ranged advantage, the movement (flight) and the versatlity advantage. Can't see why Ultron couldn't just pin both arms and steel the swords (that, can easily be seen as obviously the suit's main weapon) or just labd behind the suit, knock it face down, pin it to the ground and hack into the it.