Regarding the creation of the crossbow, its inception marked the advancement of Tibias's metallurgy by at least a few hundred years.
This is because before that, most blacksmiths had no incentive to work with iron beyond a few very specific applications, and mostly contented themselves with bronze working.
But this time, with the influx of capital and will from the ruling class above, the blacksmiths finally got the environment to work with iron and figure out various different forging techniques.
Techniques they might have figured out in at least a few hundred years.
And they all had Alexander to thank for that.
Now, though the weapons they had created were very inferior versions of Alexander, and provisions of these among the city garrison very, very sparsely due to its cost and difficulty in manufacturing, they still appeared in the fight, wielded by a very few, very well trained defenders.