Is there a tool for shapefiles or a QGIS Plugin available, which will enable me to edit the coords of a point manually ?
("tool" -f1 "Tsunami Gauge"-move x1.abcdef -to x2.ghijkl)
I do have approximate points of which I the later receive highly preceice data and there I would lie to update my so far data, instead of creating new files.
Best Answer
If you want to interactivelly change your points coordinates, one by one, I believe you can do what you want by using the Numerical Vertex Edit Plugin. I can install it in Plugins > Fetch Python Plugins and search it by its name.
After installing you will notice a new icon on you digitalizing toolbar like this . To make it active you must be editing a layer.
Click the plugin button, then click on the desired vertex (in your case the point feature). A dialog show the current coordinates of the vertex, and you can edit them.
Doing this to too many points can be quite boring.
UPDATE to QGIS 3.10
In more recent versions of QGIS, there are more options to edit a point or a vertex coordinate.
Using the vertex editor tool
Using the advanced digitizing panel
If your layer is in a planimetric SRC, you can use the advanced digitizing panel.