I think 15.5 lbs seems a bit much for a shovel.
It is rather a lot for situational gear, even if the idea is that every PC doesn't have one. Unless your PC is always carrying a shovel, it's going to encumber whenever they take it. The only reason I've not tried that system yet is that the shovel's too heavy to carry. On the other hand the 5 lb climbing claw's worth making room for in case you need it.