well, in the node editor, you could clear all the nodes out of the node editor so it's blank. Then set your traversal depth to 1 (it will be -1 by default). Then select the node connected to the blendWeighted node you want to get rid of and click the button to add it to the graph, you can then click the 'inputs' button and it should only show the nodes directly driving the node you initially added to the graph. From there, it should be pretty easy to locate the offending node.
You could select that one and click the inputs button again to see what's connected to it, and shift that connection back onto the first node before deleting the blendWeighted node... that should essentially 'erase' it and restore what was previously hooked up.
with the traversal depth at -1, it graphs all the connections until it can't find another node connected to an input/output... with traversal depth of 1, it just adds nodes immediately connected to the one you have selected in the node editor - makes it a little easier to 'walk' the graph.
