If you time your shield block right, you get a brief repel and can force a few hits in that opening phase. I think some of the Guardian shields absorb the lazer fire too.
Using the columns in the room very tactically helps, such as hiding bombs behind which the guardian would blow up when they hit the pillars. BUT then you haven't got them to hand for the latter stages.
The last two phases of the fight are rock hard though (when they start firing lazers and activate the giant swinging weapon that causes the up-draught.
Think I limped over the line with next to no weapons left but it was doable, even with not a huge load of hearts or decent weaponry.