Have a look at useful mesh editor for Unreal Engine.

Have a look at useful mesh editor for Unreal Engine called Mesh Tool that will help you edit assets, and prototype props and levels in Unreal Editor.

The tool will help you:

• Adjust exiting static meshes (fine tune mesh, make variation, fix mesh issues)
• Block out level with static meshes
• Prototype low poly mesh assets
• Work on game-ready meshes directly, not introducing proprietary mesh format

Features:

 Select & Transform

• Vertex/Edge/Face/Object Mode
• Select/Translate/Rotate/Scale elements
• Vertex Snap
• Delta Transform
• Marquee Select (Add or Subtract Mode)
• Marquee Select Ignore Backfaces or Occluded Elements
• Select Coplanar Faces
• Select Connected Parallel Edges
• Select Linked Elements
• Select Border Edges
• Select By Material/By Smoothing Group
• Convert Selection between Vertex/Edge/Face
• Show/Hide Transform Widget
• Customizable Transform Widget Pivot
• Focus on Selected Element or Editing Mesh
• Toggle Vertices/Edges/Backface Edges Display
• Hide Selection Display
• Customizable Vertex/Edge/Face Display Options

Vertex Op

• Create Face from Selected Vertices
• Delete Orphan Vertices
• Collapse/Weld Vertices
• Align Vertices
• Set as Ruler

Edge Op

• Split Edge
• Turn Edge
• Bridge Edges
• Extrude Edges

Face Op

• Draw Quad on Customizable Draw Plane
• Flip Faces Normal
• Extrude Face
• Inset Face
• Delete Face
• Delete Invalid Faces
• Duplicate Faces
• Separate Faces
• Assign Smoothing Groups
• Assign Material to Individual Faces

Texture Map (UV) Op

• Planar(Wall/Floor)/Box/Fit Mapping
• Pan/Rotate/Scale/Flip UV

Object Op

• Flip All Faces Normal
• Weld All Vertices
• Recompute Normal
• Insert Primitive
• Hide/Show Other Actors
• Auto UV

Mesh Op

• Save/Duplicate/Browse to Current Editing Static Mesh

Buy the tool for $50