You could add the spelling characteristic of "do not check spelling or grammar" to the
Emphasis style and use that style for your Italics.
Here are macros to create a separate no-spell-check style. I added the Italics code to it. Note that Italics is a toggle control. When applied to text already in Italics, it turns it off.
Instructions for Installing Macros from Forums or Websites by Graham Mayor, MVP
Code:
Sub NoSpellCheckStyle() ' SEE ALSO ASSIGNSHORTCUTNOSPELLCHECK FOLLOWING
' Charles Kenyon
' Creates a character style named "No Spell Check" in the Active Document
' Does NOT apply the style to a selection, simply creates the style
' 12 April 2019
'
Dim stlNoCheck As Style
'
On Error GoTo ErrorAlreadyExists
Set stlNoCheck = ActiveDocument.Styles.Add(Name:="No Spell Check", Type:=wdStyleTypeCharacter)
On Error GoTo -1
With stlNoCheck
.Font.Name = ""
.NoProofing = True
.Font.Italic = True
End With
GoTo ExitSub
ErrorAlreadyExists:
MsgBox Prompt:="Style 'No Spell Check' already exists", Buttons:=vbInformation, title:="Oops"
ExitSub:
Set stlNoCheck = Nothing
End Sub
Sub AssignShortcutNoSpellCheck()
'
' Charles Kenyon ---- GOES WITH PREVIOUS MACRO
' 2 March 2021
' Assigns keyboard shortcut Ctrl+Shift+Alt+N to No Spell Check style
' Style must exist
' Saves this in the active document
'
CustomizationContext = ActiveDocument ' Change ActiveDocument to NormalTemplate if style is in Normal Template
KeyBindings.Add KeyCode:=BuildKeyCode(wdKeyN, wdKeyControl, _
wdKeyShift, wdKeyAlt), _
KeyCategory:=wdKeyCategoryStyle, _
Command:="No Spell Check"
End Sub