This is probably a bit of a followup to one of the options the WoL can pick way back when the Domans first come to Mor Dhona. It's the MSQ quest "Why We Adventure". One of the kids asks the WoL what is the best way to become more powerful and the WoL can respond with "Buy weapons and armor from Rowena.".

The thing with Rowena is that for all she does have a lot of influence economically, we've yet to see her not provide what she commits too. If one holds up their end of the deal, she always holds up her end. She must drive Ul'dah's dishonest merchants crazy!

Example of Rowena doing business with other organizations: In the Lvl 68 SMN quest, it's revealed that Rowena is the one financing the Sons of Saint Coinach archeological digs. In return the Sons of Saint Coinach turn over a portion of what they find to her. That same quest also reveals that Rowena and the Ironworks have a symbiotic relationship as well. The Ironworks get access to all the Tomestones Rowena collects and in return they give her written transcripts of what is on the tomes. She even lets Y'mhitra borrow said transcripts with the payment being summaries of the transcripts. Apparently, the people who buy the Tomestones off Rowena like knowing what they're paying for!