It doesn't seem as if it requires any actual skill on the player's part that way. You just pop the ability off and treat it like a +DEF skill, or a HP barrier, making it completely passive. Plus it only ever has relevance if you're taking damage and ideally you want ways to skillfully avoid taking damage outright, rather than diminishing incoming damage. If it has HP and is treat as a physical entity that either follows after the player or circles them, you have to take care to position it or keep an eye on it if you want to chain a perfect guard off of it, or desummon it if you want to avoid your actual shield breaking. Also people don't really seem to enjoy the completely passive skills like the existing two because they're unintesting, but I could be wrong on that.