Trying to solo the Ruin Sentinels with no shield and pure melee is probably the least fun I've ever had with this game. Less fun than Ancient Dragon, even.
My desire to continue a no shield run is waning. Who am I trying to impress?
Nooo, shieldless is the most fun way to play the game.
Summon an npc if you have to!
As for the Ruin Sentinels, the attack you really have to worry about, is the spinning one, when you see them do that, just roll away (you can roll through it theoretically, but it's hard as shit).
All the other attacks are somewhat predictable and rollable through, just make sure you have AGL to 100 or 105, for ideal I-Frames.
Of course kill the first one on the ledge, and there you can practice rolling through their attacks, when you have two, it gets trickier, and you will be able to only get one or two attacks in before going into defensive mode again, but they do take quite some damage.
Try to bait their attacks, so that they attack together and try to keep them both in your screen, and if one of them isn't, just listen to the audio cues to time your roll, 'cause they're probably preparing a jump slamming or a spinning attack on you.
They were the second hardest boss to do with my shieldless build, if that's any consolation, so once you got them out, the rest is easier (up until
).
An NPC will take away some of the aggro without being too determining in terms of damage dealt, so i'd also consider that option.
Exactly because you're not trying to brag to anybody, and because a shieldless run is more fun and aggressive than a shielded one, it's worth continuing.
Also, get poison arrows or a poison weapon and stay under 40% equip load!