Here are some spells I've revised from the originals in GURPS Magic for my personal GURPS Dungeon Fantasy campaign, Felltower.
These spells have been revised based on my personal experience, the opinions and suggestions of my players, and my own decisions about what magic should be like. They are also based on a megadungeon-centric Dungeon Fantasy game, and reflect a specific approach to adventure. Feel free to use them in different-style games, but be warned - they reflect a very personal view to how they should work.
Ruling Priority Order
Body of Wind
Hold Fast & Wallwalker
Hush, Mage Stealth
Ice Slick & Grease
Paralyze Limb & Total Paralysis
Shocking Touch, Burning Touch, Deathtouch
Sleep & Daze
Stone to Flesh
Thunderclap & Concussion