The last thing we need is Siegfried to have offspring. I feel a better option would be a Student. This way, the new character would have a less complicated connection to Siegfried while also having more options for character development.
I would prefer the new face be Female brandishing a thinner blade and armor like Hildes (minus the helm) but that's just me. Knightess of Wolfkrone perhaps? That would be cool. But no broken crap. Siegfreids fighting style should stay mid tier. Period! No damage buff, no speed increase. Sieg is fast enough as it is with crazy damage if done right.