you may need,, when you parent your arrow to null,, adjust the positon and local axis,, first.
then you change null positon,, the parented item move with null.
I do not know how you set the null,, but I try with other produc arrow,,and rotate aroow by null with local axis.
(or I may set bone, then rotate the arrow. but you may not want to set bone for your arrow prop, I think)
1. load arrow prop on to the scene.
2.create new null.
3 translate null , and roatate null ,to set null rocal axis, along arrow shape.
(it may different with arrow local axis.
because,, often prop local axis, do not along the prop shape.)
you may need to change 3d view, top and front ,then adjust null rotation, with the arrow shape.
4, set arrow parented the null. now you select the null , the local axis fit to the arrow shape.
5. once you set parented,, you better not select arrow.
drug and rotate the null to adjust the arrow positon where you want. it semes easy by wrold axis.
6, now you can rotate your arrow , by use null rocal axis, along to the arrow shape.
but,,,, it can only work about,, manual rotaiton in 3d view with universal tool. ..
the cotroller parameter are not rocal axis,, so you can not rotate aroow along the shape by parameter ^^;