I was reading a National Geographic issue from about a year or two ago. In it there was an article about the Phoenicians, which then made mention of Carthage. Apparently, in the ruins of Carthage there is evidence for the use of the Bessemer process for steel refinement. Perhaps a family member from Carthage could have a trait that would decrease the cost for training heavy infantry units?

Also, since Phoenicia had a huge lumber trade, maybe those who stay long enough in Sidon, or whatever city there is now, could have a trade bonus in provinces where lumber is an export.