Roman legionaries were trained and skilled in the use of javelins, which were used as an enemy closed (or were closed in on), a disruptive “whites of their eyes” tactic that just preceded the swordplay. Augustus also reduced the century to 80 men (formerly 100, but kept the name, sounds like gov’t to me) and the legions, even when full strength, shrank to about 4000 men. But 4000 javelins arriving over the course of 1 or 2 seconds did a lot of damage, and caused loss of manpower & morale and sudden desertions among adversaries.
https://www.britannica.com/technology/pilum
The pilum was a heavy javelin used by Roman foot soldiers. It was about five feet long and had a heavy head of soft iron that made up nearly one-third of its total length. This design restricted its range but increased its impact. The soft iron head was intended to bend upon impact, preventing the enemy from throwing it back. The javelin, in general, is a shorter, lighter throwing spear compared to those used for shock combat. While spears evolved into various forms like pikes and lances, the javelin, including the pilum, retained its characteristic form for a long time.
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Whoops, from 100 to 80 got started earlier, but not standardized until Marius. My apologies.
https://search.brave.com/search?q=reduction+of+roman+legion+from+100+to+80
The reduction of the Roman century from 100 to 80 men occurred gradually during the Middle Republic (roughly the 2nd century BC) as the army shifted from the maniple system to the cohort system. Originally, a maniple consisted of 100 men (one centuria), but as tactical roles differentiated, maniples were split into two centuriae to allow for dual command by senior and junior centurions. This split standardized the fighting strength of a century at 80 legionaries (derived from halves of 160 or 120-man maniples), with the remaining 20 men often consisting of non-combatant support staff or servants (calones) to maintain the administrative total of 100.
Under the Marian Reforms and into the Imperial Period, this 80-man fighting unit became the standard baseline for all cohorts, except the First Cohort, which eventually consisted of five double-strength centuries of 160 men each. The term century (centuria) remained in use despite the drop in combatants because the unit originally denoted a civic levy of 100 men, and later because the inclusion of support staff kept the total headcount at 100 for logistical purposes.