Whenever equipped creature attacks, put a +1/+1 counter on it.
Equip {2} ({2}: Attach to target creature you control. Equip only as a sorcery.)
If you move Armory of Iroas from one creature to another, any +1/+1 counters on the first creature remain where they are.
The +1/+1 counter is put on the equipped creature before combat damage is dealt.