Would be nice to be able to welds verts together that you have selected. If it does already I am probably doing it wrong. I have my model, I go to triselection mode, select verts, I selected my verts, clicked weld and nothing happens. I do get that Im in the triModel mode and there is no like Vertex Edits… I se the triangle edits and Edge Edits but no vertex edits.
Sorry we currently do not support welding vertices, we only support welding edges. We do not support non-manifold edges, ie a mesh edge with 3 triangles connected to it. Welding vertices makes it very easy to accidentally create non-manifold geometry, so we have stuck to welding edges.
Unfortunately we have not managed to implement enabling/disabling the different “action buttons” in these tools based on what you currently have selected. However at least in UE5.0 Early Access, if I select vertices and click on ‘Weld’ it will show an error message at the top of the panel (“Cannot Weld current selection”)
It should eventually be possible to make a vertex-selection and then weld the edges connecting those vertices, but we do not support it yet.