From what I've noticed, is that if I use defend, on a mounted unit/champion, there is about a 20 second lag, before it continues on. I see the same targeting grid you are refering to, but it goes away on it's own. There is a small lag on non-mounted units, but consistantly a 20 second+ lag once on a horse/warg.

Got it too.

yeah.. when not mounted.. it's fairly quick.. you get the shield immediately.. but it sort of looks like it doesn't wear off (or gfx not disappearing) until that character's next move ends? (or i might have misremembered)