AB Sword Number 9. Thousand Spikes (Masterpiece) from the Korean webtoon Knight Run. This sword was used by Feizer, Chief of the Northern Order in the series.
Wiki link: https://knightrun.fandom.com/wiki/Number_9._Thousand_Spikes
AB Sword Number 9 in its passive state.
AB Sword Number 9 in its active state showing the spikes hidden within the blade.
Main reference images.