Over on my post about Identifying Magic Items in GURPS, Archon Shiva had a good suggestion - a cumulative penalty for Analyze Magic.
If you follow the Seek spells, you're looking at a -1 per spell you have to ignore, which would suggest a -1 cumulative penalty. Item has three enchantments on it and you cast Analyze Magic at -0, -1, and -2.
If you go for a steeper penalty, like the Healing spells, it would be -3 per spell. So, 0, -3, and -6.
I'd probably make any failure end the process - you can't try any more on that item. Other casters can try with the same penalty since it's not cumulative per se, but ignoring known enchantments. You can tell them which ones to ignore but they'll still catch the difficulty of ignoring known spells. Again, much like the Seek spells.
For games where you want magic item identification to be difficult, this is probably the way to go. It's time consuming (1 hour base casting time), expensive (8 energy), has enough prerequisites that aren't on the path to much besides Analyze Magic . . . and would be penalized and failure would end the process for you.
Why I won't use this in my DF game is because I don't actually want magic item identification to be that difficult. Time consuming (30 minutes with Analyze Magic-20, which high point value wizards can easily reach), tiring (and thus means time sitting around waiting for Wandering Monsters), and occasionally fails adding to the same - that's all fine. But I want them ultimately to succeed and figure out what items do. The fear of cursed items and missing out on powers that take spells to identify before you can use them (Does X or Y on command, say) means it's still important. It's worth doing in the dungeon. But otherwise it's a mechanical process bound to succeed. It's something you can pay for in town.
When making decisions about game rules, you have to consider what you actually want. If you make something hard because "it should be hard," that's fine - but if you want it to be in-game hard but require it to happen, it's just a character point tax. People will pay it to make it happen. If you want it just not to be done at all, don't make it difficult, make it impossible - DF and PC enchantment of items, for example. No, you can't do that. Period. Done. Move on. If you want it to happen all the time but in a specific way, just set it up so that happens. Since my goal, ultimately, is to have people know what their items do but worry there are curses so you shouldn't just swing the random sword you found confident it'll be fine . . . I make identifying magic items pretty easy but not trivial. And once they're back in town and spend some money, I'll just pass off the info to them so I'm not tracking all of their item's secret powers. Your rules have to serve the game you want to have.