The punchline is that, while a warlock, he is built like a twink and useless in meelee combat. Very much not a hexblade type. So the dead-goddess sword does him no good at all.
Next panel shows the sword surrounded by flames, angry scribbles, and those "menacing" kanji from JoJo's Bizarre Adventure
Little sidenote; those are katakana, not kanji.
To give more context, they're entirely different writing systems; kanji are words and verb-roots written in Chinese characters, katakana simply represent the sounds of loanwords and onomatopoeia. In this case the “menacing” part isn't represented by a word with meaning but by the sound of rumbling thunder, writtem as ゴロゴロ (goro-goro). There is no dictionary definition for this, only sound, so they're written in katakana instead of kanji.