The Guardians in The Legend Of Zelda Breath Of The Wild are huge octopus-like robots. They were probably built by the Sheikah. We’ve seen the huge ones in the overworld, and smaller ones in the Shrines of Trials. But recently Nintendo posted a screenshot of a new sword-wielding variant locked in one on one combat with Link.
The Legend Of Zelda Breath Of The Wild reveals more content
Something notable is that Link is wearing the blue tunic. Which at this point actually means something. Sort of. Aonuma has already said that it’s plot relevant. And since E3, ALL new footage seems to have come from a more recent build of the game (like on Game Center, and at the Game Awards). In all of the new gameplay footage he hasn’t been shown wearing these clothes
So, if this is from the same build (or at this point, likely an even later one), this is after he passes the “certain point” in the game where he gets his blue tunic. BUT not yet at the part of the game where he gets the Master Sword. Which we know he gets because we’ve seen it (or, he has the Master Sword, but is not using it? which raise even more questions).
With a game with as much freedom as this one seems to have the specific shrine he’s tackling likely doesn’t mean anything. As if it’s like rest of the ones that we’ve seen. The only prerequisite is that you find the shrine. But some environments will very likely be difficult to traverse before certain points in the game. We could interpret this as a rough sort of guide for a point in the game by which we’ll have had the opportunity to have encountered this variation of The Legend Of Zelda Breath Of The Wild guardian.