For whatever reason, your attachments are in different file formats. To save the document in the docx format you might try something along the lines of:
Sub Demo()
Dim StrFlNm As String
With ActiveDocument
StrFlNm = Split(.Tables(1).Cell(1, 5).Range.Text, vbCr)(0) & " " & Split(.Tables(1).Cell(1, 2).Range.Text, vbCr)(0)
StrFlNm = "C:\Users\" & Environ("Username") & "\Documents\" & StrFlNm
.SaveAs FileName:=StrFlNm & ".docx", FileFormat:=wdFormatXMLDocument, AddToRecentFiles:=False
End With
End Sub