.warnp should accept roles only below your max role. Also added a custom error message

src/NadekoBot/Modules/Administration/UserPunishCommands.cs

@@ -323,6 +323,14 @@ namespace NadekoBot.Modules.Administration
             public async Task WarnPunish(int number, AddRole _, IRole role, StoopidTime time = null)
             {
                 var punish = PunishmentAction.AddRole;
+
+                if (ctx.Guild.OwnerId != ctx.User.Id &&
+                    role.Position >= ((IGuildUser)ctx.User).GetRoles().Max(x => x.Position))
+                {
+                    await ReplyErrorLocalizedAsync("role_too_high");
+                    return;
+                }
+                
                 var success = _service.WarnPunish(ctx.Guild.Id, number, punish, time, role);
 
                 if (!success)

src/NadekoBot/data/strings/responses/responses.en-US.json

@@ -80,6 +80,7 @@
   "greet_off": "Greet announcements disabled.",
   "greet_on": "Greet announcements enabled on this channel.",
   "hierarchy": "You can't use this command on users with a role higher or equal than yours (or mine) in the role hierarchy.",
+  "role_too_high": "You can't use this command with roles which are above your highest role, unless you're server administrator.",
   "images_loading": "Images will be reloaded within a few seconds.",
   "insuf_perms_i": "I have insufficient permissions.",
   "insuf_perms_u": "You have insufficient permissions.",