Is it possible that a shardblade can take on different form based on their user's idea of an ideal weapon? Szeth's shardblade looks like that because that's how most Shinovar's blades looks like. Dalinar shardblade form looks like a huge sword because that's how most Alethi swords look like. What would have Shallan's shardblade if she had summon one? Would it looked more like a knife? It would kind of make sense since if Kaladin ever received his shardblade, it would have taken a form of a spear.
