[TheForge] How did the cross pein hammer come to be the standard?

[xlch58 at swbell.net]

As I was forging today, I noticed how often I reach for a straight pein 
hammer, but rarely use the pein on my cross pein.   Watching other 
smiths it seems they also reach for a straight pein or 45 degree pein 
most often.    So I was wondering how the cross pein came to be the 
standard and how it became associated so closely with the smith?  Anyone 
know?

Charles