L ittleheart - Each of his tales contains a small core of truth.
O arni - Their blade twists in the deep waters; it does not heed the foam above.
S olosimpi - Each began alone, but their simple tunes grew together.
T 4. - "It's like steel wool," said the king, "but worse, and pre-cut for us."
T evildo - From scourge of the north to a whisper in the dark, the prince's sad fate.
A lalminórė - Twice walled in mithril (well, almost), a small region of fair woodlands.
L impė - Like
miruvor, it's pathetic, eh?
E riol - Hesitant, the sailor erratically greased his boat.
Tevildo's cats were a major power in Tolkien's early works; by the time of LotR, cats' main claim to fame was that Queen Beruthiel had some - remembered mostly in a saying (whisper) about finding your way home in the dark. Poor Prince Tevildo (though that's what you get if your name literally contains the word 'EVIL').
And Littleheart - your reasoning is amazing! Mine was much simpler: he's a tale-teller, and his name can be literally translated as 'Small Core'.
Just one to go! #4 includes a terrible, terrible pun, but to be honest once you figure out which part is the straight clue there's only a few options even without the cryptic parts.
hS