The Whimsical Cursed Sword is a Manga/Manhwa/Manhua in english language, Action series, english chapters have been translated and you can read them here. You are reading chapters on www.mgeko.cc fastest updating comic site. The Summary is

The story is set in a fantasy world of swords and magic, but this isn't a typical fantasy world since the technological progress have advanced so much that smartphones are everywhere!!

Everyone lives a peaceful life until one day a brother and a sister find a very strange sword.