This kit is does not contain any cursed objects (such as a cursed pens), but is instead a simple and safe way to start investiagting curse magic and more specificaly the use of words (in written form) as a way to make magic manifest.
 
You don't need to use this kit to just curse or perform malificent magics (Black Magic), but lets be fair the kit sounds so much cooler if we call it a 'Cursing Calligraphy Kit' compared to naming it something like 'Witches Caligraphy and Magic Set'.