“Pressure” to change the line width in the Pen Tool Stroke.
“Corner Tool” to round out node corners that are ill regular.
The ability to change a line by grabbing the line with the node tool and pulling or pushing it in a different direction. This can be done with Affinity Designer while using the Pen Tool by holding down the Command Key on a Mac and move the line without creating another node.
These enhancements would greatly aid the ease of use when using the Pen Tool.