See, there was my problem - it never even occurred to me to try using the fire bracelet.  Suddenly, the fight became shockingly easy; he didn't even get a chance to call in the wolf pack!

Thanks!  Now to prep for Zirduros.

Currently slowly moving through this (the PSP is rather low on my priority list atm), but having a good time with it all the same.

Some of the bosses can be crazy hard, but I like how it's that good kind of "I-can-do-this-if-I-just-try-one-more-time" hard, instead of the "oh-f*ck-this" hard.

That said, and I'm sorry to sound like a cocky prick, but the succubi fight was shockingly easy.
I died only once (there's always some trial and error), but the second time round I got them without any trouble (playing on Normal).
Attacking them at the same time is key, and you should focus on taking the blue one out first since it seems to take most damage from your sword, but if you just level regularly and try to get the best equipment available at any given time, it's really not too hard.

That's how I felt for the first half of the game. Then I started running into bosses that would kill me five times in a row even after I spent time leveling up before them. So I cheated and chose to lower the difficulty from then on. I used to relish the challenge, but now I lose my patience and just want to make progress.

the succubi were the only bosses i beat right away on nightmare

but most of them gave me hell, particularly the first boss in the lava zone, the one in the ice area until i figured him out, this game sure doesn't hold your hand (totally forgot how to beat him), and of course the last boss. he was brutal and i was almost tempted to lower the difficulty. but i think it is hard to give up when you went that far and so i pulled through.

At least they allowed you to lower the difficulty.  I was playing Ys I & II Chronicles on Hard, and was doing OK until I reached the bat boss at the end of the mine.  I spent a half hour trying to beat him, and couldn't get him down below 3/4 health.  I leveled up to the max, and still couldn't get him below 1/2 health.  That was when I discovered I couldn't lower the difficulty.  So, I had to start all over on Normal.

I finally finished the game today, and I can say with full conviction that the bosses in the latter half of the game were considerably EASIER than in the first half. Out of all boss battles, the one in the first dungeon, that demon/statue type thing, Ellefale was it?, kicked my ass the most.
I literally spent over 30 tries on that thing.

I would say it has to do with the fact that you're just generally more powerful and versatile later on in the game, so I didn't really get much resistance until the very last boss, and even that one only took me, like, 5 tries or something.

I didn't think I'd be inclined to try some of the harder difficulties, but after seeing the bonus stuff you get, I might actually try after all...

But first! 3rd Birthday!