Air carrier Captain reported navigation displays disappeared while on approach and First Officer hand flew aircraft to a safe landing.

Narrative

While at FL350; First Officer's (FO's) Primary Flight Display (PFD) showed Control Wheel Steering (CWS); and an amber VTK (Vertical Track) with no Flight Director (FD). No single FMC scratchpad message. Since FO was pilot flying and my side was unaffected; I switched Autopilot to CMD A. While searching for FMC FAIL non normal; indications disappeared. First Officer then switched Autopilot back to command B. Later; while on ZZZZZ arrival into ZZZ; at around 6;000 feet; both flight directors disappeared with no other amber lights or messages. Autopilot was in CWS. We were approaching ZZZZZ1 fix and needed to turn. Asked FO to turn off Autopilot and hand fly while I informed ATC of our situation. After some confusion on the radio; I requested priority handling and informed ATC that we were having flight instrument failures. Since it was VFR; and we were on an RNAV arrival; I asked for 5;000 feet and radar vectors while we tried to trouble shoot. Decided it would be better to get vectors for visual to XXL. Landed uneventfully.