It's difficult not to awaken stunned/riddled enemies when traited with Fighter of the Shadow as it is so Multi-target focused. If War Chant's range is too much for you like you say I would suggest removing any trait points you have in 'Demoralizing Anthem'. Additionally, after a while you will get use to knowing roughly just by eye how far your chant goes, then you will be able to have a fair idea beforehand whether it will arouse the ire of nearby enemies, or awaken stubbed ones, before you use it. That is the sort of thing that only comes with practice though, it can't be taught.
Also it's worth mentioning that just because we have a skill doesn't mean it's useful in every situation. The Challenge in the Library at Tham Mirdaim is one such example; simply don't use War Chant there. Hope this helps.
[center][I]"No, you are right. There is strength in these hobbits yet,
and if they need to repel dangers from outside, they will do so."[/I]