Bronze blades are far too early period for SCA....
The Celts were pretty advanced in some odd ways considering they didn't really have cities or architecture in a modern sense of the word, and I'm sure some of them(they were a collection of groups, not one group), especially the Irish, had quite consistent and high quality bronze. The people we know as the Irish and eventually the Scottish are originally from Spain, and the darker people who are known as the Tinkers are actually more native to Ireland, probably having been there 6 thousand years longer than the people we see today. They are also the ones who built all the stoneworks and even Stonehenge in England. Anyhow, this older group had developed bronze to a pretty fine art it seems, but their invaders had them outdone on just about every other aspect of technology, especially logistics and armor. Combining their technologies proved to be quite effective, and the new Irish further developed it, and also started mining gold, some of which can be found in the coffin of King Tut. Ireland was one of the few places in Europe to have any tin, so their bronze more commonly had 10-15% tin. They also did seem to be able to add phosphorus to it via manure. I forget how they dealt with the resulting nitrates, but I think they just burned away. Maybe they burned the manure first, I honestly don't remember. If you are mainland Celt, the only source of tin was to import from Ireland, which was done, or to get it out of the Germanic regions which are now Switzerland and Austria. These sources were not very accessable so the price was very high, and the region was also not Celtic and thus there may have been cultural boundaries. Mainland bronze, as a result, was unlikely to have more than a very tiny amount of tin in it, and I believe the lead content was also higher, but this was purely impurity. Brass was later obtained by trade with Rome, who I believe learned that art from the Greeks(along with just about everything else).
If your persona is Irish or Scottish you are going to luck out on quality if you want to stay completely historical on it. 4th Century BC might have still seen some bronze in use, but by that time even the Celts were fairly ahead of most of the rest of the world in terms of the use of iron. Only Africans were ahead in this regard(interesting that they never managed to stay ahead with such a big headstart). Early iron mostly came out of England and Scandanivia(which was not Celtic). After the first time the Celts of Gaul conquered Rome and sacked the capitol, Rome put more importance on iron work, having leared from their defeat and took it to a whole new level. This tech spread as did Rome, and by the fourth century AD I believe they had all they way up to the border of Scotland conquered. These areas they conquered were heavily Romanized, and so a mainland Celtic persona of 4th AD would reflect this heavily. If he were any sort of warrior he would have to be a Roman auxillarie, because to bear arms of any sort was forbidden amongst the conquered people, unless they enlisted. If he was from England, same thing, though culturally a bit less Roman at that point. Irish or Scottish was a different story. These two groups were feared by the Romans, so they must have been pretty fierce at this point, yet the Romans also traded with them heavily, so they must have gotten along to some degree. It would not be absurd to see a 4th AD Irish Celt with a set of Lorica Segmenta or Lorica Hamata protecting his torso. Nor would it have been absurd to see him carrying a gladius or a spatha of Roman origin. Interestingly, you would likely also see items from Scandanavia and Upper Germania. The Irish and Scottish at this point in time filled the role which later the Norse did, that of the wild barbarians who everyone feared, but who were really mostly explorers and traders. 4th AD gives you quite a huge range of options for your persona, though I still believe bronze weapons, with the possible exception of a spearhead, are not typical at that point, they might have even gotten you odd looks from other warriors.
Many of my family members are getting back into SCA, and I figured I'd join them, and I always wanted to make a few of these blades.
