User blog comment:B214/Question and Answers 6/@comment-26293136-20161107123620/@comment-1359322-20161108134042

Finally remember where it was stated:

"And this is his so-called new technique. The Balance Breaker of Blade Blacksmith! Except, in this situation he won’t be able to use his holy-demonic swords. He can only use the holy-swords. And conversely, he won’t be able to materialize these knight troops while he is using the holy-demonic swords."

- Volume 10

So he can't use both. Though Ishibumi already hinted in his blog that Kiba's SGs may combine. I'm guessing the new ability of the SoB in V19 is the key. That depends to be seen though.