Most La Tene and Hallstatt swords do not have the kind of damage that Bronze Age swords have. The regular notches sometimes found on (particularly Late) BA swords in a region from Spain to Hungary are more likely due to ritual destruction than actual combat, though. Unfortunately, because this ritual destruction might have taken the form of ritual combat, it is sometimes very difficult to see the difference between actual combat damage (such as might be seen at Tollense) and this show-damage (most of the Thames stuff). Things like curled tips can occur when a sword strikes bone just as well as when it it thrust into a piece of oak.

Bronze swords are sometimes so brittle and poorly made that they must have been made specially for sacrifice, though, particularly in the Late Bronze Age. And while I do know of repaired or shortened swords occurring in graves, I do not know of them from the Bronze Age deposits.

Now, if you then look at the Iron Age, many swords are also ritually destroyed (curved, bent, folded, or just broken up). However, what makes things harder for the Iron Age swords is that they are much more fragile, are much poorer preserved, and have often been found during gravel scooping or other highly destructive activities. There are not many sites where the iron is as well preserved as the bronze, and consequently I do not know if any study on use-wear on iron swords has been done. I also think it is highly unfeasible, both because of preservation issues, but also because it is very difficult to distinguish ritual destruction (such as at Illerup) from battle damage. I have tried to look into this stuff in the context of the Dutch examples, and the few swords we have from Hallstatt graves are much better preserved than the Rhine river finds. Even then, the grave finds are not preserved well enough for any use wear.