Edison format ruling
Mermaid Archer

Card text as printed in this era① Once per turn: You can target 1 face-up Level 3 or lower monster you control;
equip that target to this card (Max.1).
② Gains 800 ATK while equipped by this effect.
③ If this card would be destroyed, you can destroy the monster equipped to it with this effect, instead.
Rulings
- If both this card and its equipped monster would be destroyed at the same time, you can't use the ③ effect to prevent its destruction.
Rulings data courtesy of Format Library — formatlibrary.com. Spotted an inaccuracy? Flag it in the Edison forum — sourced change requests get reviewed.