Is there any Norse mythological figure associated with victory?
Any god or mythological being in Norse cult associated mainly with victory?
In a round-about way, I'm wondering if the valkyries are closest. They chose those fallen in battle to go to Valhalla. Obviously the chosen weren't victorious - they died, but that's only the mortal realm. In the wider sense they gained "victory" in being chosen by the valkyries to enter Valhalla, and presumably by being "heroes" for others to follow. A personal "victory" in the minds of those who lived by Norse mythology. Not one I'd care to achieve, but one they aspired to.
No, none that is exclusively associated with victory.
The closest we get is probably Odin, who is said to be able to give victory in war. Note however, the Sigrdrífumál, with accompanying prose introductions, in which it is told that Odin promised victory to the king Hjalmgunnar, but the valkyrie "Sigrdrífa" ('driver to victory'; she is actually Brynhilde) defeated him instead, so Odin's power is only worked through intermediaries. There is a part of Njal's saga in which a group of women weave witha gruesome set of tools: human skulls as loom-weigths, innards as the warp, etc, and sing of how they are valkyries and "weave victory".
If there would have been a norse personificiation of victory, the name would likely be Sigr.
What about the god Týr? I've found some examples of warriors carving his rune on their weapons to obtain victory. Or was he like Odin, someone to whom commend yourself before battle, that not necessarily granted victory?
@Rodia Tyr was slowly going out of fashion (he likely used to hold the position Odin had), and by the end of the pagan age, he, and probably also Thor, was more likely a god you prayed to for personal success, while Odin was the god for kings and lords. If you went into a trial by combat, Tyr would be the appropriate god to pray for, if you were fighting a war with another king, you needed Odin's favor