As pointed out by @soloooy0 elsewhere, it does not make much sense for Romans to build an arsenal, since an army camp is almost always a much better choice:
- can construct siege engines and train citizen soldiers
- costs only 200 wood more (500 of army camp vs 300 of arsenal)
- more health and capture points
- fires arrows by default and can be garrisoned by soldiers to shoot more projectiles
- large garrison capacity and heals units inside
- can be built in neutral and enemy structures
This patch removes siege engines from the production queue of the army camp, so if you want siege engines, you'll need an arsenal. Without it, the army camp, though less ‘overpowered’ than it currently is, is still a very decent structure. Instead of having the a subset of barracks units, the army camp can now train advanced melee infantry.
While at it, this patch also adjusts the parent, since the army camp file inherits hardly anything meaningful from template_structure_special.xml.