I'm far from a modeling guru, but you might try the bend function which lets you draw a 'base-line" (left click+hold+drag to draw) then make a second bent line (left click+hold+drag) to warp the selected vertices. The up/down location of the first 2 dots will affect how the object is bent. Pressing F1-F3 to align the view might help.
Another possibility is the "Pipe" plugin. To use it, draw a curved line (create line) that follows the center of the object you're making (ie, the curved sword blade). Again, pressing F1-F3 should help keep the line flat. Next draw a separate line loop that will be what the cross section of the sword will look like (ie probably a diamond). Select both lines and run the Pipe plugin. It will draw polygons along your curved line that match the looped lines shape.