Can the falcon only bring stuff from the owner to another hero?
Or can the owner also fetch stuff from another hero?
The owner can also fetch stuff.
From the Reference Manual (Thames and Kosmos), page 6, right column, 'The falcon':
"Two heroes can exchange as many small articles...at one time as they like...One of them must be in possession of the falcon."
and from the errata on the offical website:
"Q: If a hero uses his falcon can he transport small items between any two other heroes?
A: No. One of the two players involved must be the owner of the falcon."