No idea about the pre-Migration period, but I'm pretty sure northern Germany only became famous for some arms-production centers by the Middle Ages. The chronic instability of the region during the Roman period (with all those tribes wandering towards the limes in search of fortune) ought not have made for very solid industrial base or all that much material wealth overall.
Of course, the Baltic region still had a fair bit of valuable stuff to export - amber, furs, walrus ivory etc. - and the people who could tap that trade could of course get pretty rich indeed, duly allowing them to aquire various luxury items (including swords) from quite far away.
Insofar I'm aware of the basic "grunt" of the Migrations Germanic armies was the humble spearman (an axe and/or long knife would have made a cheap and effective sidearm; the pattern repeats with the Vikings), swords and such being the purview of the wealthy elite (and lucky looters) for purely economic reasons already. Indeed, by what I've read of it, even more complex and impressive types of spear, such as the long-shanked angon throwing-spear (extremely similar to the contemporary Roman spiculum, which had replaced the old pilum), were something of "prestige weapons" only the better-equipped warriors had.
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