Many names do seem to have less than appealing meanings. As a child, I was shocked when I discovered that
Rachel meant "sheep" and
James meant "supplanter." In defense of
Portia, it could be derived from Latin portionem (nominative portio) "share, part, portion." Alternatively,
Portia could also be derived from Latin porta "city gate, gate; door, entrance." I don't know why Behind the Name decided to go with the least flattering of all the possible meanings. Maybe they have something against "The Merchant of Venice."