I agree with Delboy; I don't think it's anything to do with solder. As a retired electronics engineer and using a soldering iron every day for decades it doesn't look like solder splatter to me at all, just corrosion and verdigris. As for the lines on the face it would be near to impossible to lay down solder on a surface like that.
I still go for the 'defaced die' explanation unless someone can come up with an alternative plausible explanation.
Mike.