A blue feather symbol in front of a component in an assembly means this part was loaded lightweight. This essentially means only the basic information of a 3D representation and the name of the file have been loaded into RAM. This helps load large assemblies quickly.
A file will be loaded lightweight if the settings in the options under performance and large assembly mode are active; or if the lightweight checkbox in the Open dialog is checked.
To reload a single component into memory to edit its parametric information right-click the file in the feature manager tree and pick Set to Resolved; or simply select it in the graphics area and that part will be loaded into memory. To load all the parts in a single action right mouse click the top icon in the assembly and pick Set Lightweight to Resolved.