pothos.org

I couldn't resist! After literaly homerical battles, slaughters, rivers of blood (Scamander), deadly blows and duels, hundreds of corpses, what, in the end Diomedes had to suffer?

Look at the link...

http://s1246.photobucket.com/user/IamSy ... 7.jpg.html

Yes, you saw it right.... a bloody "bloody" finger! And what care does he receive from this fellow warrior, Sthenelos! What attention, what love!

In any case, this is not the case of which Homer speaks of and I do not know where did the one who drew it imagined it from. Maybe its a story we don't know of.

Since the description places it during the fight for Achilles' body I would guess the story is in Quintus Smyrnaeus' continuation of Homer, though I have not read it myself.
And don't despise a cut finger, they can really smart!