who *is* "Kwalish" anyway?
Kwalish was one of Tim Kask's characters from Gygax's campaign. He never owned such an apparatus though. Gygax just named it after the character because he thought it would be funny.
But I'm fine with Melf's Acid Arrow, even though I don't know or care who Melf is.
Melf was one of Luke Gygax's characters - the name stood for "Male Elf".
As for the other people with spells named after them...
Mordenkainen ('s Magnificent Mansion) = Gary Gygax's character
Tasha ('s Hideous Laughter) = Not named after a character but after a real girl who wrote letters to Gary Gygax.
Bigby ('s Interposing Hand) = NPC created by Rob Kuntz who became a henchman to Mordenkainen
Leomund ('s Hut) = Len Lakofka's character
Drawmij ('s Instant Summons) = Jim Ward's character (it's his name spelled backwards)
Otiluke ('s Freezing Sphere) = Unknown
Tenser ('s Transformation) = Ernie Gygax's character (it's an anagram of Ernest)
Evard ('s Black Tentacles) = Unknown
Rary ('s Mnemonic Enhancer) = Brian Blume's character
Otto ('s Irresistable Dance) = NPC created by Gary Gygax who became a henchman to Tenser
Nystul ('s Magic Aura) = Unknown