I'd like to know the whole sentence because the の doesn't make sense.

Suppose the の is merely a typo,

その自重を支える翼持つ「冒険者」よ

means:

Hey, the "adventurers" who have the wings to support their weight, ...

In this context, it's obvious that

自重（じじゅう）= the weight of oneself = one's weight .

自重（じちょう）する means to "to take good care of oneself" and it doesn't fit in this context.

I'd like to know the whole sentence because the の doesn't make sense.

その自重を支える魂の翼持つ「冒険者」よ

means:

Hey, the "adventurers" who have the spiritual/imaginary wings to support their weight, ...

In this context, it's obvious that

自重（じじゅう）= the weight of oneself = one's weight .

自重（じちょう）する means to "to take good care of oneself" and it doesn't fit in this context.