The Summoner savegame file is a whopping 265KiB (270,755 bytes). With such a small size it is terribly easy to pinpoint several key locations to cheat by editing.
Now, get your standard Hex editor and get to work. Here are the addresses and what they do.
File: Summoner\savegame\sumoner?.sav (quicksave.sav) — 265KiB
|000150ED||Gold||It's beside the letters INVT|
|0002781F||Joseph's skill points|
|000279A7||Flece's skill points|
|00027B2F||Rosalind's skill points|
|00027CB7||Jekhar's skill points|
This should get you up and going make you as rich as you need to be. Very useful for buying the Dreadblade from the merchant in the hills in Medeva! By editing the skill points attribute, you can give yourself as many free skill points as you need. By changing the XP, you can go to any level you want.
By changing your level back to 1, but keeping your current XP level, you will level up to your previous level instantly, gaining that much HP, AP, and Skill Points. Great trick! Only drawback is that you lose all skills you're not supposed to have at that level. The main use of this option really is to pump up your HP and AP.