c-sanchez, just one idea (there are many ways to reach it)...
lets play with symmetries...
- The start point
- Select the top faces and use Extract to copy it
- Select the two vertices on the bottom face of the new object
- Connect [C] them
- In body [B] mode select the new object
- Use Rotate [RMB] to rotate it around the picked axis
- Confirm the command [RMB] after you find the desired rotation
- Scale Radial [MMB] the main object around the picked point and axis
- The result
- Select the vertice as shown and use Intersect [LMB]
- Pick the axis along vertice will be moved
- Pick the plane of intersection. Use the main object edge loop for that
- The result
- Now, the other vertice
- Getting the direction vector
- To get the plane parallel to the edge we need to select the edge and use the option "[1] Save edge normal" (right in the information line)
- After accept [RMB], that is the result
lets play with symmetries...
- Starting using Edge Loop in the midle of the main object followed by Loop Cut to remove the bottom faces
- We need to select the two vertices as shown and Connect [C] them
- Now selecting the vertical edge loop
- After use Loop Cut we remove the left half of the main object
- That is the result and we show the other object again
- Lets use Intersect again, selecting the vertice and vector as shown
- We hide the main object and pick the plane of intersection
- After accept [RMB], that is the result
- Then, we select both objects in body [B] mode and apply Weld
- For the start point we have a quarter of the desired object
- After selected the vertical face and use Mirror [LMB] we get the half of the object
- In order to mirror it vertically we need to make the two bottom faces one by selecting and Dissolve [Bksp] them
- With the bottom face selected we apply Mirror [LMB] again
- That is the result
- In order to continue to making the sword, we Loop Cut the bottom arrow