I intend to, now that I realize no game out there will probably ever have a Royal Guard feature.
A lot of games have a timed defense system like the ones already mentioned, except no games - that I can think of - have a defense system like Devil May Cry 3's and 4's.
Darksiders 1, God of War, and Metal Gear Rising: Revengeance all have guard systems that allow you to reduce damage if timed normally, but if timed perfectly, allow you to counter or redirect attacks. War and Kratos could redirect and counter attacks with perfect guards, while Raiden could only counter with perfect guards, otherwise reduced damage, deflections, and "turtle-ing" happens with normal guards.
Bayonetta, Darksiders 2, and DmC: Devil May Cry all have evades in place of guards that gave you benefits; Bayonetta has guards too, when unlocked. In Bayonetta, you get to slow down time through Witch Time. In Darksiders 2, Death would summon his Reaper form to counter attack; it has a really strict timing, that or the game is too hectic or the combat wasn't "appropriate" for the monsters. In DmC, Dante has an Angel dodge and Vergil's Tricks that covered distance and the (OP) Demon dodge that slowed down time during the animation and gave a damage boost.
Fighting games all have defense systems, which is a given. It depends on the series, though. Some series allow infinite guards, chipping, guard gauges, etc, but all series have unblockable attacks to prevent stalemates. Ninja Gaiden borrows Dead or Alive's combat system - the same could be said about Devil May Cry (and other Capcom games) and Street Fighter - so Ryu has a powerful guard system and counter is a separate command. As OP and important as guarding is in Ninja Gaiden, enemies have unblockable attacks, like grabs, and prevent the guard from making the game too easy; once you stop guarding, you either have to attack, counter, or evade unless you want to take damage.
The Legend of Zelda: Skyward Sword, Demon's and Dark Souls, Kingdom Hearts, and the upcoming Final Fantasy XV and Lightning Returns: Final Fantasy XIII have defense systems as well. Skyward Sword has a guard system similar to Darksiders 1, God of War, and MGR: Revengeance, where you guard at the right moment and stun the enemy allowing for a counterattack. Why is it here instead? Well, it uses motion control, making it a little different compared to the others. From Software's games have an important defense system with stamina. Guarding makes a huge difference in a series with a default difficulty of hard. While parrying and riposte when mastered play a vital role in quickly taking out dangerous foes parry-able and/or riposte-able. It's a slower and more risky system of defense compared to other games. Kingdom Hearts has a simple defense system. Time it right and all following attacks are guarded against. The issue is that some characters, especially in earlier games, are sluggish and countering might not happen.
Final Fantasy XV is a game that holds many promises and has a lot of hype. Nobody knows what's going to happen. In Final Fantasy XIII, one ability, Vendetta, functioned similarly to Royal Guard where characters "take" damage and return it multiplied percentage-wise. Screenshots and videos show that you can guard and evade in FFXV, but whether or not a more complex defense system will appear is up to Square Enix. Who knows, maybe Vendetta or a Royal Guard-like system will appear in FFXV. It's not out of question since FFXV aims to have a spectacular combat system. The last entry to the Lightning Saga or Final Fantasy XIII trilogy features are more action-based combat system. A recent video showed that timed evades and guards yield benefits like staggering, stuns, etc. It's a little weird considering that Final Fantasy XIII is more turn-based RPG than action RPG even though Lightning Returns is something of an action, turn-based RPG.
So games have defense systems, but DMC3 and 4 have a defense system that isn't instantly gratifying. All the above have defense system that when performed correctly allow you to reap the benefits immediately. Royal Guard doesn't do that; power is built up the more attacks are successfully guarded. Releasing right after an attack will only do a fraction of what Royal Guard is capable of. Lore-wise, Dante builds up anger after every hit, guarded or not. That anger is transferred into energy which he can release for a powerful attack. It's not slow, however, but it takes time compared to other games and their defense systems.
In many cases, it's probably better to evade and/or parry and then counter rather than guard. Guarding means you'll take damage and be worn out. Evading just puts you out of the way of danger, but enemies can still follow-up and attack, though maybe not as easy against a guard. Parrying can force an attack in another direction, making follow-up attacks much more difficult than against an evade or guard. Even though games aren't usually super-realistic, something might need to explain why a guard is much more effective than evading and parrying, like an electric shield or something. Royal Guard does that by having Dante's anger as fuel and games having perfect guards to negate all damage.
A character who's full of anger and hatred or easily angered could make a fairly acceptable answer as to why guarding is much more effective. Kind of like Asura, except that Asura's Wrath was a really weird game/anime. Guard, guard, and then *BOOM*! Explosive angry counter. Or a character who can literally absorb kinetic energy and store it for future use would make for an awesome mechanic - future protagonist's power for future inFAMOUS game idea here! Basically, Royal Guard could return in unusual and unexpected ways from unexpected developers.
