Romans could not solve a problem which is after the sword queeches, the iron sword became really soft, could be snapped easyily. therefore romans had short swords instead of long swords, (otherwise, snap...
)
But Han had some technology, such as tempering and Point hardening, which was very helpful. Chinese solders could have a iron sword around 60-80 cm long, and it is the best length for fighting.
Also the Hardness of Romans weapons were around 100-400 HV (normally, short sword was around 200 something, the hardest was a knife, aroudn 700 HV.
people found some iron sword during the Warring states, the hardness up to 560 HV
Hardness of Qin's bronze Sword were around 150-300 Hv
Hardness of Han's iron Sword were around 500-1200 Hv.
And i can tell u guys what kind of tactics did huns use to aginst Roman's and Han'
They fire lots of the arrows to the air, therefore Romans use their shield to guard top of themself. at same time some Huns fire horizontally. Then use cavalry to RUSH to the Romans.
But Han's had a weapon called wu gang che. 6 metre long, 4.2 m wide (might be smaller. ) pikes were in the front of it and big shield on the top and sides, and also, it can carry a few crossbow man as well.
In the battles, Han placed Wu gang che in a circle or build a defense line,Use crossbow man to defend and cavalary rushed to Huns base camp.
Crossbow man had different version of croosbow as well. They are called one shi, 2 shi up to 10 shi. ( one shi equals to the force is need to left up around a mass of 30 Kg )
from range of 300- 800 meters.