i doubt the 13MS are looking for Baam, because Zahard hates him, probably. he's the one who made them so he should be able to set the restrictions to the "king". it's whoever Zahard chose
Zahard ordered Ashul Edwaru to make them.
Also, even though Zahard might have been able to set the 'restrictions' on them, I doubt he actually set 'no Arlene's child can wield these weapons', afterall, Baam was able to ignite Black March before, be it that the 'spirit/ghost' of 13 MS have a mind of their own and ignites for whoever strikes their fancy.
Also, Zahard killed Arlene's baby, so he believed the baby to be dead. Baam was not in the tower when the princess were fighting over those cursed weapons, So there was no reason for Zahard to 'restrict' him then, and Zahard had been 'inactive' since before Baam entered the tower.
Plus the 13 MS was created back when there were still 13 of them, Zahard and 12 GW, Arlene and Viole included, if the 'ghosts' or 'curse' were created at the same time with the 13 MS, baby Baam wouldn't have existed yet that time of 13 MS creation, how would Zahard put restrictions on just Baam because of hatred then?
The 13 MS was then used to make the princess killed each other, Enned said Zahard did not want to choose a wife, thus the 13 MS's curse. If the curse was put then by Zahard to prevent any of the princesses to be able to meet the requirements to be his wife (the one who could wield all 13 of them), then the only restrictions Zahard would have put in with the curse to prevent such thing would be "only irregulars can be the chose one" (since those princesses would be regulars) or "nobody with Zahard's blood can be the chosen one" (thus no princesses can succeed, and that include the so-called 'princes' as well).
So either way, there is a chance for Baam to be the chosen one... and that's just my opinion.