I did some testing on pts:
used character: v16 redguard dk template
armour: 3x agility, 4x sheer venom, 3x essence thief, 2 maelstrom's daggers
no passives skilles, no cp used
twin slashes gets always buffed
unstable flame gets always buffed
poison arrow gets always buffed
lethal arrow gets the poisoned status effect buffed
flurry gets the first 5 hits buffed
acid spray gets always buffed (in my opinion this is an aoe skill, but I might be wrong^^)
burning breath gets sometimes buffed (still need to figure out what causes this)
soul strike gets always buffed (might need to be changed, could be too strong)
dawnbreaker always gets buffed (WHAT?)
cleave never gets buffed
blade cloak never gets buffed
volley never gets buffed
meteor never gets buffed
caltrops never gets buffed
It seems as if some cone aoe skills count as single target. That should be fixed, especially for dawnbreaker.