easy as funk, climb the ladder while holding the katana, do some parkour, and proceed.

Kill the Fast Headcrab, Kill the zombies and headcrabs, proceed with the katana, there's a narrow ledge, but don't worry, there's a small platform to save you from falling, you still have to be careful though. the platform gets overtaken by the ledge, so just jump. be sure to strafe to the right to stay on the platform. do some more parkour with the katana in your hand. kill the Zombie Torso by yeeting the katana with the gravity gun, proceed. there's a saw wheel. when the zombies come, gravity gun yeetus the saw wheel at them. there's also other props that can easily break some bones, yeet the meathooks at dem haters. there's a big ol' table here, can be grabbed and yeeted, but then you'll eventually have to use your katana. Proceed.

there's sum' fast zombie boys. fight 'em by yeetusing the katana. the katana can insta-kill the Fast Zombies. keep killing zombies and HCs by yeeting the katana at them, you'll notice that this guide is also helping with Zombie Chopper, as we only used weapon_physcannon thru out the whole guide, but don't worry, Father Grigori will shoot the ones that are outta reach for your katana. he gives you a SPAS-12, don't use it, stick to the physcannon. there's some fast zombies, they're pains in the ass, just don't give up yet! the elevator is coming, assuming you pressed the button. press another button, to go down. the door closed, you are safe (for now at least), they're building up back there. So you'll need a propane tank. you may get hit in the gregory during that scrap, but 'ey, you sure did get 'im! grab a healthkit. and the katana and proceed.

leave the katana somewhere near, and mow thru dem faguettes, you can use the katana., ♥♥♥♥ it, it's too hard, use ya SPAS-12, now take the recommended ammount of Dedotated Wam, and it will help you with headshots, jump to the house. throw some saw wheels at the zombies, and then punt the headcrabs.

after going into the house in d1_town_03, you apparently go back to d1_town_02, so dodge some zombies and headcrabs. go into another house, now you're on the roof., wait for the cart.
Shoot up some zombies while waiting, the cart is here? good, take the katana to the cart and release the handbrake.

proceed with the katana. Protect Grigori. there's gonna be fast zombies. there's a fire, it will go out eventually. after killing a horde of zombies and headcrabs (including a poison zombie and it's headcrabs), you have to proceed. hurry while he holds the gate, and DON'T FORGET THE KATANA.

do some parkour with the katana in your hands. down there, there's headcrabs. fight them, but keep the katana close. do more parkour, go for a dive, there's a barnacle up there, kill it however you want.
now that you're near Ye Ol' Choppa, don't activaye it, do a duckjump, so you don't need the chopper, and kill the zombies.
carry the katana to the end of the tunnel. there's zombies, kill them.

You escaped Ravenholm! but there's still snipers. kill the fast zombies, kill the snipers, kill the soldiers. Don't lose the katana! don't even worry about Winston. carry the katana to Highway 17.
Noriko will bring the buggy out, you'll be driving it

You did it! you carried the katana to the end!
leave it on a crate and move on with your gaming career