Got a little problem, in my server I made a guardian farm in my house and it's really slow and they still take around 2/3 hits to kill with a maxed out sword. No guardians spawn outside the area which is good. What can I do to make it better?
Hurt them a bit before they reach you with fall damage or lava so that they take less hits to kill, and add an item filter so you don't have to spend all that time sorting. It sounds like alot of work but I assure you it pays for itself after around 5 double chests of manual sorting
There is a tutorial on the Minecraft Wiki for Guardian Farms, but I think Guardians count towards the hostile mob cap, so you will have to light up the surrounding underground areas of the farm (128 bloc radius as i recall), to limit the spawning of other hostile mobs ...
The Meaning of Life, the Universe, and Everything.
Try making it fully automatic, with manual intervention after lighting up all of the caves underground. To do this, you need to place lit campfires or soul sand and wither roses on top of the hoppers. That way, the guardians will be killed, while still dropping items, albeit not as frequently as if you were killing them with a looting III sword. Make sure that the guardians fall out of the water onto the campfires/wither roses, and that it is a sufficient enough fall distance so that they aren't killed by impact, but by the campfires/wither roses. If you want to get higher drop rates, then create an opening facing towards the campfires, leaving a space for you to kill them manually with your sword, when you have time. It still works, even if you don't kill them with your sword. This will continuously kill the guardians, so they may spawn "faster", since there are less mobs in that chunk, because the guardians are being quickly killed off. More will take its place.
Hope this helps!
EDIT: explanation as to why to add the campfires/wither roses