Sarisio: 7 options (see screenshot attachment for in-game description):
1. Cost: 20%. Gives you food (never use it).
2. Cost: 20%. Gives you gold (it is something like 200 gold per level, despite what other people say - never use it, it is a waste).
3. Cost: 30%. Full Heal of HP/PP (also useless).
4. Cost: 30%. Teleport to safe place (Velegarn?). Cheaper to buy crystal.
5. Cost: 40%. 1 Stat Point to 1 character.
6. Cost: 50%: 1 Skill Point to 1 character.
7. Cost: 100%. Each character receives 1 Skill Point.
Talisman charges from 0% to 100% in proportion to average level of party and amount of exp gained. I didn't find true proportion yet, but it is probably around 40% per each 2.5 levels.
Some of the options you consider useless might be useful if you find yourself in trouble. Of course, that shouldn't happen if you are playing well, but sometimes it might be necessary if you make a mistake.
1. Suppose you are playing Hardcore (or are in the desert you've mentioned), are out of food and cereals, and forgot to take a crystal with you. This may be enough to get you out of trouble. Also, if you don't have Knowledge of Terrain and are unable to cross the desert, using this option repeatedly might allow passage.
2. I note that there doesn't appear to be an experience boost option, so getting gold and using that gold to buy items to exchange for experience might be useful. Also, in a speedrun (assuming the Talisman is allowed), this can be a way to get the money needed for potions and scrolls. (If you kill a strong monster at a low level, your talisman should charge significantally, allowing you to use the talisman more often in a speedrun than in a casual playthrough.)
3 and 4. Suppose you are about to be attacked by Cursed Hounds and your party is in no condition to fight. Furthermore, you don't have enough food to rest and don't have a crystal to escape. This could get you out safely (though since 1 is cheaper, choosing it and resting may be a better option. How much food does it give you anyway?) Also if you are stuck in the desert and option 1 isn't enough to get back to town, option 4 might make sense.
One interesting thought: Would it make any sense to hold off on leveling so that the talisman charges faster? This might be a way to ensure you get enough skill points to level up the stats you need.
Maybe some day, I may play with the Talisman and intentionally delaying level advancement if it works this way.