Oh, another weirdo has appeared. I first thought she'd be something like the Lady of the Lake... but yeah. Okay, another sword. Then all of them will certainly pop up sooner or later. Harem? No Harem? Don't really care about that at this point, but actually I'd prefer a non harem for this.
Logically speaking, Alba could probably wield two swords at the same time - at least in theory. That is, if he has the strength and skill to actually pull that off. But usually you'd expect a holy sword with a distinct persona such as theirs to place some condition on the contractor... like "I am thyn owne swerd, thou shalt welde non other blade but myn." or something.
At least, if it has some pride left. And see, Miss Holy Sword of Darkness (aka Rita) definitely told Alba at the end of chapter one when she ordered him to delete all contact info for other weapons right away. No two timing... I doubt her sister swords are an exception, but who knows. I certainly hope she won't budge on that or there's a rule in place where you cannot contract with more than one holy sword no matter what. Otherwise another weirdo among her sisters could decide to brute force a contract through because reasons, just like Rita did. Because he sure did not actually consent there.