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Use a hacksaw to cut of a length of steel equal to the total combined length of the blade and handle. Clamp the steel down using a vice while you cut it. Cut out the dagger pattern you sketched out previously and lay it out onto your length of steel. Carefully trace the shape of the blade and handle using black marker. Alternatively, you could temporarily glue the template onto the steel using water-soluble adhesive. Use your hacksaw to cut around the pattern, removing as much excess metal as possible. The idea is to get the rough shape down, but you do not need to achieve the exact shape of the blade during this step. Continue holding the metal down using a vice. Alternatively, you could use a power jigsaw during this step. Set the jigsaw on its highest speed and pause the process frequently to lubricate the blade with paraffin wax. If you do not lubricate the blade, it could overheat. Note that the portion of the metal that will lie beneath the handle needs to be less wide than both the blade and the anticipated size of the wooden handle. Finish shaping the exact outline of the dagger using a metal file. You do not need to sharpen the blade at this point, but you do need to trim the blade to its actual shape. If you need more power than a metal file can achieve, you could also try using a belt sander or jewelers saw. Mount the blade to the edge of a table using your vice and file in both side edges so that they slope evenly down toward the center. The edges should slope in on both the top and bottom sides. Use a metal file to bevel the edges. Always file in the forward direction and never file back and forth. Use both hands and apply as much pressure as possible. Keep the blade clamped at waist height. Doing so will make it easier for you to put your body weight into the process, which will make it easier for you to finish the beveling without straining your muscles. The ideal bevel angle is about 30 degrees. Keep this angle as consistent as possible around the entire edge of the blade.
Cut down the steel. Lay the pattern over it. Rough cut the general shape. Sand it down. Bevel the blade.