The nature of the ban on arms within Rome\'s pomeri

[Tarbicus]

But they are still arms which had to be brought inside the city, and maybe stored before distribution.

They were trophies won by individuals in single combat during battle, and proudly nailed above the doors of the victor's home for all to see. I doubt they were in any condition to be reused after the weather had done its business with them for a few years.