Changed MessageUpdated to use Cacheable as well, after discussion with Volt.

src/Discord.Net.WebSocket/DiscordSocketClient.Events.cs

@@ -65,12 +65,12 @@ namespace Discord.WebSocket
             remove { _messageDeletedEvent.Remove(value); }
         }
         private readonly AsyncEvent<Func<Cacheable<SocketMessage, ulong>, ISocketMessageChannel, Task>> _messageDeletedEvent = new AsyncEvent<Func<Cacheable<SocketMessage, ulong>, ISocketMessageChannel, Task>>();
-        public event Func<Optional<SocketMessage>, SocketMessage, ISocketMessageChannel, Task> MessageUpdated
+        public event Func<Cacheable<SocketMessage, ulong>, SocketMessage, ISocketMessageChannel, Task> MessageUpdated
         {
             add { _messageUpdatedEvent.Add(value); }
             remove { _messageUpdatedEvent.Remove(value); }
         }
-        private readonly AsyncEvent<Func<Optional<SocketMessage>, SocketMessage, ISocketMessageChannel, Task>> _messageUpdatedEvent = new AsyncEvent<Func<Optional<SocketMessage>, SocketMessage, ISocketMessageChannel, Task>>();
+        private readonly AsyncEvent<Func<Cacheable<SocketMessage, ulong>, SocketMessage, ISocketMessageChannel, Task>> _messageUpdatedEvent = new AsyncEvent<Func<Cacheable<SocketMessage, ulong>, SocketMessage, ISocketMessageChannel, Task>>();
         public event Func<Cacheable<SocketUserMessage, ulong>, ISocketMessageChannel, SocketReaction, Task> ReactionAdded
         {
             add { _reactionAddedEvent.Add(value); }

src/Discord.Net.WebSocket/DiscordSocketClient.cs

@@ -1291,10 +1291,9 @@ namespace Discord.WebSocket
 
                                             after = SocketMessage.Create(this, State, author, channel, data);
                                         }
-                                        if (before != null)
-                                            await _messageUpdatedEvent.InvokeAsync(before, after, channel).ConfigureAwait(false);
-                                        else
-                                            await _messageUpdatedEvent.InvokeAsync(Optional.Create<SocketMessage>(), after, channel).ConfigureAwait(false);
+                                        var cacheableBefore = new Cacheable<SocketMessage, ulong>(before, data.Id, async () => await channel.GetMessageAsync(data.Id) as SocketMessage);
+
+                                        await _messageUpdatedEvent.InvokeAsync(cacheableBefore, after, channel).ConfigureAwait(false);                                        
                                     }
                                     else
                                     {