modifying or making weapons

[AnubisCK]

I know in the arms & equipment book there rules on modifying weapons. with banded or spiked but also remember reading about making new weapons but not sure where. as i have a character who wished to use a ball and chain but wants it to be 2 handed use for extra reach and bigger for greater damage but unsure how to make alterations to the stats

 

[Big Orc]

I would also be interested in these rules, if anyone can supply their location.