Found an old piton - question

I pulled this seven, eight-inch Lost Arrow piton out of the bottom of a crack in Eldo today. Just sitting there.

Obviously it’s seen better days. My curiousity is: I’ve never seen a piton with a little notch in it like this one has. It feels smooth, like it was machined that way. There is no irregularity in the metal which would indicate it corroded Or was damaged. I can’t think of any advantage it would confer-but I am far from an expert on pitons!
Just curious if any of you old timers who actually climbed with these things could shed some light.

That is a heavy nut tool. 

That's a Chouinard "Long Dong" Lost Arrow.  Some were machined with the notch to use as a nut removal tool.
Edit: "Super Long Dong" aka: "Nut Cracker" nut tool, specifically made for the purpose. 

Piton/nut tool - yes, it was really a thing for a brief time.

I guess if you’re carrying all that iron already, there’s no reason to bring an additional nut tool!

awesome, very helpful, thanks guys   

I had one BINTD  pounded it in somewhere... can't remember where....  sure it was truck though. 

Honestly? That thing looks pretty mint.

A very nice find and as said above "Super long dong" a later version. Does it have U.S.A. on the reverse??

https://books.google.com/books?id=CRhPDQAAQBAJ&pg=PA10&lpg=PA10&dq=Chouinard+%22Long+Dong%22+Lost+Arrow&source=bl&ots=OXNCgQrb3p&sig=ACfU3U1SnKq5r0JAJSiK3W0S1D3oSMPEmQ&hl=en&sa=X&ved=2ahUKEwi8kMbPpPbpAhWRbc0KHX1cDKMQ6AEwAnoECAoQAQ#v=onepage&q=Chouinard%20%22Long%20Dong%22%20Lost%20Arrow&f=false