...the target of an assassination shouldn't be so much obvious, bit instead should be an excuse to frame or to get in trouble someone else...
..for example the perfect target for an assassin is Kaye tesarani, Hemlock's fiancee, in order to get the excalation to relations among Sczarni and sheriff Hemlock (--> maybe Korvosa Guild would finally stop sczarny expansion and get in trouble Jubrail Vishki..) or Vana Deverin, mayor Kendra brother wife, in order to put in disgrace deverin family and change Sandpoint leadership....
maybe the assassin isn't required to kill someome, but just let someone else be killed:create a near-completion assassination attempt and then bring and hide the evidence of crime in someone residence...
ideal target for the failed assassination is Kendra Deverin, and the person to be killed is Belven Valdemar (a bold move of Scarnetti family to acquire Valdemar shipyards through Sczarni contacts)
or..maybe... the rising of Runelord slumber is preceded by someone who will eradicate every possibility of interfering... madame Kvashti is then the perfect target, and the patron is an agent of a distant Runelord, one that will rise up after someone else demise...
possibilities are infinite...