ToME WikiRedNaga: as suggested on the spoiler page, i'm reporting this suggestion here.
The text for Eol's quest seem to hint at a possible peaceful solution to the quest. It would be nice to be able to win the quest even without killing Eol, maybe by beguiling or tricking him. I've not examined this idea deeply, but maybe this could be accomplished by talking to him, probably related to an high character CHA, to character race or maybe to wearing or giving him some particular items. Since he would be attacking you while you have to get next to him (without harming?), this could be even harder than just killing him. The reward could thus be different as well (Eol gauntlets spring to mind, but they're probably too powerful a reward for it!).
I know this is very generic, but it's... well, just an idea. And i'd like to hear what others think about it.
NameLess: I think that ToME is not really a game about peacefull solutions, it is about going around killing stuff and collecting rewards. Having a peacefull ending to one quest would be to different. In my opinion anyway.
RedNaga: yes, that's true for the main game, but quests are the perfect place where to put non-conventional behavior: Maggot's quest is already non-violent, and i think even Nirnaeth can be ended without killing anything (with maxed stealth you should be able to pass near everything without waking it). Lostsoul too are often not very violent... 
Further, i was suggesting an *alternate* ending for the quest. If you so wish, you could still kill Eol and complete the quest anyway. As i said before this should end up ideally harder to do than just killing him, so in the end it would add to the challenge.
NameLess: I suppose you're right... perhaps you could talk to Eol five times to calm him down instead. Eol will then thank you and create some kind of magical artifact for you to use.
RedNaga: that's quite what i was thinking, but even more limited: maybe each time you talk to him some sort of CHA check is done, and you need to pass three-four of them. Maybe race could be a modifier (dark elves = bonus, high elves = malus). Alternate option: he could be susceptible to the charm spell, that when cast succesfully on him would end the quest (this should be possible to do in LUA). At least this will give some chance for Eru followers to use their mind spells 
.
As for the reward, a randart light source or tool might be nice, since they are so rare elsewhere (actually, i'm not even sure randart lights are possible) and they are so going to be more useful than the lantern of the magi, which i usually discard soon after receiving for some better trueart.
TheFalcon: Randart light sources are definitely possible, both torches and lanterns.
BucketMan: I actually really like this idea! A choice...what to do... Ok, let's ask the question: why exactly is Eol going to the city in the first place? In the books, wasn't he going to attempt to retrieve his wife? How about, when you encounter him in the caves, he explains that his wife has run away, and he is simply going to find out what happened and get her back. He asks you to *escort* him to Turgon. You can, of course, decline, kill him, and complete the quest normally. However...if you accept Eol's quest offer, you abandon Turgon's quest completely, and move to a new chain of quests. Turgon no longer trusts you, so you don't get the lantern, and you will never be given the 'Cut through the trolls' quest. Instead, Eol thanks you, but gives no immediate quest reward at all, but elsewhere later in the game, a new quest is opened up to you that you wouldn't be able to see if you killed Eol. Presumably this would also have an affect on the Maeglin quest as well...since Maeglin was Eol's son. If you help Eol, maybe Maeglin doesn't ever try to attack Minas Anor, and instead some other quest could result. The decision whether to help Eol could easily spawn an entire new set of storyline quests...that could be very interesting.