This is great except for one thing. It applies the +Int bonus to ALL Con saving throws. It should just have the green notification saying it's +5 to concentration, but not actually add it in.

Is there a way to add the Level 14 feature "Song of Victory"?

how did you get the AC bonus to be the INT modifier, rather than a fixed value?

I think it would be easier to custom make your melee weapons for this, since the only way I can think of, for a magic item to allow this, is by changing the STR stat, which is not what you're trying to do