Armory of Iroas — ruling 1

The +1/+1 counter is put on the equipped creature before combat damage is dealt.

Armory of Iroas — ruling 2

If you move Armory of Iroas from one creature to another, any +1/+1 counters on the first creature remain where they are.

Armory of Iroas : règles, fonctionnement et interactions (MTG)

Armory of Iroas is one of those cards players keep asking about. Here is, in plain words, what its official text says, the rulings published by Wizards of the Coast, and the combos players actually run.

Official card text

Whenever equipped creature attacks, put a +1/+1 counter on it. Equip (: Attach to target creature you control. Equip only as a sorcery.)

How it works : Armory of Iroas

Original English text — Wizards of the Coast / Scryfall

#1November 10, 2020· Wizards of the Coast
The +1/+1 counter is put on the equipped creature before combat damage is dealt.
No other card is named in this ruling.
#2November 10, 2020· Wizards of the Coast
If you move Armory of Iroas from one creature to another, any +1/+1 counters on the first creature remain where they are.
No other card is named in this ruling.