Goat format ruling
Fusion Sword Murasame Blade

Card effect (current official text)Equip only to a Warrior-Type monster. It gains 800 ATK. While equipped to a monster, this card cannot be destroyed by card effects.
Rulings
- If this card is face-down on the field, it can be destroyed by effects that destroy Spell Cards.
- When you activate this card, the opponent can chain a card like Magic Jammer that will negate its activation and destroy it.
- If you equip this card to Freed the Matchless General, Ryu Senshi or to a Warrior monster you control when you have Frontier Wiseman on the field, it is negated and destroyed.
- If a monster equipped with this card is Set, or removed from the field, this card is destroyed.
- This card can be sent from your hand or your Deck to the GY by the effect of Confiscation, Delinquent Duo, etc.
- If the monster this card is equipped to has its Type changed to anything but Warrior, this card is destroyed.
- Q: If I equip "Fusion Sword Murasame Blade" to "Spirit Reaper," would "Spirit Reaper" be destroyed or would this be an illegal activation? A: You wouldn't even be able to target him with it at all. "Spirit Reaper" is not a Warrior. It would be an illegal activation in this case. If "Spirit Reaper" were turned into a Warrior through "DNA Surgery", equipping "Fusion Sword Masamune Blade" to "Spirit Reaper" would cause "Spirit Reaper" to destroy itself through its effect.
Rulings data courtesy of Format Library — formatlibrary.com. Spotted an inaccuracy? Flag it in the Goat forum — sourced change requests get reviewed.