It took me a moment to figure out what you meant but I can see how it looks like the hand is backwards. The thumb is actually out to the side though, in a grasping position, and is passing under the palm of his hand. So we're seeing the back of his hand with the top of his thumb sticking out from underneath. The lighting just makes it tricky to discern properly.
def one of my fav ( i admit that i am not super fan of angels even if yours are technically crazy good) i love the lighting , and also it's cool to have make him very skinny his strenght his somewhere else . veerryy good job !
another mind blowing illustration by the awesome Algenpfleger! gorgeous rendering. one thing that looks funny to me, though is the right hand. it looks like it has a sixth finger that had been shopped off, or it seems kinda mutated to me. other than that the brush strokes and lights were handled so good. I would love to see this as a DD. cheers!