Hello,
Thank you Jens for your precious comments about giant fighters !!
I hesitate to use too another alphabet 

but I prefer continue with my bad english !! 
I wonder why it's so corroded while really old katars or swords 15-16th century) have still a nice blade. 
Only the way they keep/ preserve it ?
The composition of the steel could have an influence ?
Was this one only made of iron or did it sleep under water or wet soil during a century ?
I try in another forum specialised in archeology-minerals if they can help for date it, we'll see what they say... 
Kind regards