Blobs can either be in blobspaces or in the table's partition/fragments, so at least you can be confident regarding the 'in table'.

sysblobs might be a bit 'unreliable' regarding your desired information (dbschema should be a better choice), and if there was a
conflict with documented behavior, this could probably count as a bug.

Unfortunately the two places where I find sysblobs explained are a bit vague as well:

"The sysblobs system catalog table contains information about the location of dbspaces and of simple large objects."

.... so what might be the location of a dbspace... ?

Column Type Explanation
spacename VARCHAR(128) Name of partition, dbspace, or family

.... and what a partition's name?

Strange, but I don't think many people would mind.

And as an addtl. hint (how dbschema finds out): if syscolumns.colmin is greater than 0 for a blob columns, it is the blobspace
number for a 'detached' blob column - if it's 0, it's an 'attached' blob.

Regards,
Andreas