How to get Acina's Tricorn without having Vektor as a merchant anymore

Hello,

I found this very interesting and maybe it is a also helpful for others. So you can hire Vektor as a Crew member for you ship in Tikawara. The problem is that he is also a merchant who is selling Acina's Tricorn, which is probably the best headgear for a Sharphooter for example. Once you hired him, you cannot get this item anymore. Not even from Himuihi, who is the merchant standing next to Vektor. However if you kill Vektor on your ship, Acina's Tricorn becomes available in the store of Himuihi. :)

By the way if anyone knows a way, how to get Kuaru's Prize (unique ring sold by Kipeha in Ori o Koīki), even if you already slaughtered everyone in Ori o Koīki, then it would be also a helpful information to know. :)