I can only agree with everything Olearyf2525 and Sega Chief have said. Mandatory grinding can never be the solution to a game's lack of difficulty. Rather, you should try to tackle the root of the problem, which is the major imbalance of the junction system itself. Stat boosts from magic should at least be cut in half (probably even more) so that the player isn't allowed to become super-powerful at the very beginning. As somewhat of a compensation, natural stat growth should be higher, this way spending hours upon hours drawing certain magic and/or playing cards for refining magic won't be a necessity. If I were to go for a FF8 difficulty mod, fixing the ratio of junction stat boost vs natural stat growth would be the first thing I'd do.
Unfortunately, we currently have no way of modifying junction boosts, that's the only reason why I never even bothered for a difficulty mod, seeing as in FF8's case, simply boosting enemy strength wouldn't be enough. Not with the (in my opinion) completely broken junction system.
The second major problem stems from the fact that a lot of the game's more powerful spells become available way too soon. You can refine Curaga, Tornado, Quake and others from cards and various items on disc 1 already, and that simply shouldn't be possible. In most rpgs, there's a steady increase in power of the available spells which draws nearly through the enitre game. In FF7 for example (assuming you play without grinding and just moving through the game the normal way) you have nothing but Level 1 magic available until you reach Fort Condor/Junon. At least for me, this is usually the point where Level 2 magic starts to show up, and then it's again a long way before reaching Level 3 magic (for me usually on disc 2 somewhere at Gaia's Cliff/Northern Crate, which is about a little more than halfway through the game, considering that disc 1 is the longest and disc 3 is actually rather short). It's similar in FF9, where you aquire your first Level 2 magic near the end of disc 1 and Level 3 magic no sooner than mid-disc 3 (Gurgo Volcano).
Most rpgs follow the same setup (more or less), as it always has been considered a well-working and maybe even integral part of game design. Yet FF8 doesn't follow this seemingly basic rule at all, as it grants the player access to a wide range of high-level magic in pretty early stages of the game. If it were to follow the established rules of spell progressing, it would need to look something like this:
Level 2 magic becomes available at late disc 1, Level 3 magic including Quake and Tornado become available around late disc 2/early disc 3, and high-end magic like Ultima, Meteor, Full-Life and the like shouldn't be available until mid-to-late disc 3 (maybe after aquiring the Ragnarok).
An important change to achieve this would be to make card refinement not available until later stages of the game, and certainly not in Balamb already! Giving this ability to one of the beginning G.F.s can just be described in one way: bad game design.
Anyway, those are just the most important points that a difficulty mod should address before anything else, imo. Once a reasonable junction system and magic availability has been established, the fine-tuning of enemies can begin, but just boosting enemy strength without solving the major gameplay issues first would be rather pointless.