Weaponry is weapons taken all together. Modern weaponry, advanced weaponry, an array of weaponry.
It is a mass noun with no plural, and it names the equipment as a class rather than any one piece. The -ry ending collects things into a class, as in machinery, jewellery and crockery, and it always makes an uncountable noun.
1nounweaponryWeapons taken all together.
“The army showed off its latest weaponry in a parade through the capital.”
weaponry is equipment.
Middle English
wepen
English
weapon
English, today
weaponry
From weapon + -ry. weapon comes from Middle English wepen. From Middle English wepen, from Old English wǣpn, from Proto-West Germanic wāpn, from Proto-Germanic wēpną (“weapon”), of unknown origin, possibly from Proto-Indo-European wēbnom. 2
Etymology from Wiktionary, CC BY-SA