Darucas: Hmm, it's been a long time since I finished this game, but the situation you describe is the same I was in some years ago.

I played a melee character with a two-hand weapon, backed up with the Tribal spells. The ones that can put enemies to sleep, make them flee... And some amount of diplomacy. This build was said to be ill-advised. Well, turns out it was actually quite fun to play and allowed for some fun tricks, even during the last third.

So melee seems viable, even more so with a shield, and so does Tribal magic. The main issue with Lionheart is that the team clearly didn't have the time/means to properly fine tune the last third, and I was under the impression that the whole balance during a playthrough was uneven because of that.

Having said that, apart from the usual action-RPG tricks (explore, go back later), there's a system which saved me quite a few times (especially as a two-handed character):

The Target interface. It's in the UI somewhere, or hit 'T'. You can manage speed or criticals/damage with it's slider, and aim for the limbs or head. I found it did boost my chances and attacks against fast enemies, casters (which I could stun aiming at the head), or giants (aiming for the limbs to see them stumble). It's all in the probabilities and your reflexes (don't forget the active Pause!), so this system was a boon.

Healing and mana potions are really balanced to be last-minute (well, split-second) boosters too, it's unusual, but I don't remember having too much issues with that. There are other boosters that can help, and Detecting Traps and Stealth are best activated in dungeons and crowded scenes (you gain XP just for hiding around, like in the Elder Scrolls games).

As for respec, I don't think there's any, however there are ways go turns things to your advantage.

You could try a prototype mod called Scion of Lionheart: https://www.moddb.com/mods/scion-of-lionheart/downloads/scion-of-lionheart

It's a demo of sorts to show how much balance and skills can be changed thanks to the modding guide laid out by the author. It becomes totally unbalanced 10 hours in, both because you'll be a demi-god, and because some random events are coded to keep above your level, thus crushing you hard. Still, it can be a good way to gauge what's coming up and try another, more informed build later. The first part is story-rich enough to be replayed at least three times.

Last thing I can think of: you can import your character and restart a playthrough. This can give you a nice boost, and better loot (for a second playthrough of course, but maybe also earlier than a normal, level 0 game, thus enhancing the last part, possibly?).