I'm Squinting Hard But Py Eyes Keep Slipping Over The Words - Tumblr Posts

Van Helsing's letter both entertains and frustrates me. My LD is such that when I don't understand something I read my eyes just skip over it until I get back to a part that makes sense. In VH's case I enjoyed the way it was written to convey a Germanic flavor of ESL. But then several turns of phrase threw me off. Am I understanding correctly that Jack sucked gangrene out of VH's wound...with a knife? I'm having trouble picturing that. And the wound was caused by... someone. A colleague of VH's? A peer of Jack's? When his knife slipped? Why are these people brandishing knives at each other? And how did gangrene instantly set in and then get sucked out? That's not how gangrene works, is it?