Sorry, but my eyes see much differently than those who have commented.
IMHO I see that either the front sight base has been welded to add metal and then shaped with a file into what we see in the first photos --OR-- the entire front sight base has been removed and replaced with this
(exhibiting much restraint here not to call this front sight a MONSTROCITY) 
and silver soldered on.
I am very sorry, but it is the WORST front sight job I have ever seen on a Luger. No matter how functional it is, it sure is
UGLY.
The only way to fix this to make it look "normal" is to re-barrel, or remove the front sight base and ring from another Luger barrel, perhaps one that is shot out, and then have it fitted to the end of this barrel that has been turned down to accept it.
In any event, none of those changes can happen without affecting the existing blueing.
?? Is this an original barrel? or one that was made from scratch by the "inventor" ??