I'm sure others have noticed the curious similarity to the sword of Tindrem and the Christian Cross. While I fully acknowledge the parallels are minor, there are some principles that are interesting to me.
Here we can clearly see the sword of Tindrem. Through minor simplification, it isn't hard to imagine this becoming something more along the lines of the well known Christian cross.
While the sword of Tindrem lends itself well to the "crux commissa" shape, which was one of the many ways that a gibbet would be constructed for the act of gibbeting, the "handle" part could just as easily be extended just a bit further. This isn't in the lore, but it isn't hard to imagine a similar shape being formed.
However, I don't imagine the Tindremenes donning the crux as a shape of reverence of a martyr, but rather them using the crux as a symbol of Tindremic power in a similar way to how they use the sword. So a simplified version of the sword of Tindrem would likely look like something similar to:
Mats also happened to mention that "Nave" had to do with the architecture of a church which was important for the reason it's named the way it is. Assuming that the name "Nave" is Tindremic in origin, this would potentially mean that their churches at least have a semi-similar setup to the shape of Christian churches (usually in the shape of a crux immissa). This was a part of medieval architecture, and was in part inspired by the Roman Basilica (how I imagine the Library of Tindrem to actually look more like -- but don't get me started on how I imagine places to look, we'll be here all day.).
So interestingly enough, I wonder if some Christian iconography (like symbols on the coat of arms or on a tabard) may be entirely accurate through the iconography of the Sword of Tindrem. If the people using them are Tindremene in cultural heritage and/or representing the Tindremic Empire, I'd consider it wholly possible that we might see a few familiar "cross" shapes around Nave but with an alternative meaning than what we're used to.
In particular in colonies where they've been separated from "Tindrem proper" for some time, I can see them taking their own paths and potentially becoming shorter and more "X" like, but still representing that concept of pride and heritage.
Just some musing on the matter.