I like the ninja clan stories in overwatch …overwatch can give us a rival clan for shimada …a playable character also from that clan .
For example a Samurai with dual sword ? or a very high mobility character with dual sword
it is extremely likely that we will see the leader of the Hashimoto (or one of their champions) in the roster in the future. But there is an extremely serious narrative problem that still needs to be solved befor in all shimada story: Kiriko 
.
The community has noticed for some time now that Kiriko’s biography is extremely inconsistent with that of the Shimadas (age, date of Sojiro’s death), and the last short story has on the one hand clarified some doubts about the functioning of the Shimada weapons that everyone has been wondering about for years and how they evoke an almost spiritual energy. we could define it as a mix of the two things: faith in animism that takes shape in technology. But on the other hand Kiriko ruins this fantastic feeling by putting an excessively “magical” discourse in a shi-fi context again.
an explanation that could have been given in the last short story could in fact have been that it is the Shimadas who give shape to that technological energy, driven by the ardour of their ideals. it’s certainly better than putting the whole discussion (for the umpteenth time) on magic, with the fox being summoned just because yes, and Kiriko simply being magical instead of maybe justifying it with her grandmother infusing her medical knowledge into the Yamagami art of tool-making (almost like Mercy with her biotic technology).
sorry for the OT: in any case a villain character Hashimoto would be very good. but at this point he must also balance the magical exaggeration that Kiriko introduced on the opposite side: “abusing” the technological side by making the tiger’s ardor less valiant, whose legends against the dragon are very recurrent in japanese folklore. making him almost dependent on technology to demonstrate his ardor could be an interesting comparison that puts the shimada brothers in the center of the two extreme balances: spirit and technology (kiriko / hashimoto), rebirth and old values (Genji / Hanzo). it’s a nice picture… but it must fit into the shi-fi context that is overwatch, and define the events well.
as a weapon I don’t know. I think a sword would be a bit banal. I imagine instead a more vile weapon like a spiked ball in a rotating gameplay that highlights its chaos… or a stick, to vary a bit the usual weapons in overwatch.
I dont think we have any primary sword weilder in overwatch …genji’s is just an ult