Take with a grain of salt. These are just the adjustments I'd make. 

[hider=Criticism and Suggested Changes]
Suggestions are chronologically ordered. 

1. "hitting the floor and bouncing up over the face" - Difficult to envision. Very specific, complex sequences of physical actions are difficult to convey, so try not to be rigid with them; it's why one may notice a lack of structured combat sequences in some literature, but there's still instances of combat. 

2. "oblivious dumb face" - Unless oblivious modifies dumb (which it shouldn't, being an adjective), you'll need a comma (as you probably know); the greater issue is the overlap of these two adjectives. While one could make a very minor distinction between the connotation of these two adjectives, a Venn diagram of "dumb" and "oblivious" would be almost one circle. Keep one. I'd choose "dumb," as a face is easier to imagine being dumb than oblivious. 

3. "The pooch... paws" - This description interrupts description of the action. One may be tempted to describe the dog as soon as he's mentioned, but hold off until the action is finished being described. 
 
4. "jammed" - change to "jamming" 

5. "jamming into it and staying up with its embedding" - Understood, but awkward. Consider rewording with use of the word "suspension" or "hanging," or remove all together. What does the reader lose by not knowing the door is actually embedded into the wall? 

6. "peasantry" - Perhaps change to peasant; alternatively, change "cottage" to "shack" or another noun implying shoddy quality, which thereby implies the poverty if its inhabitants. 

7. "but remained relatively calm otherwise" - A door has not only been kicked in but sent flying across the room into the opposite wall, wedging itself into that wall, and suspending itself in the air, all in the presence of a no doubt frightened dog. The cottage has also shaken with the force. Nothing is calm here. I plead with you to remove. 

8. "yeomen squires, guardsmen, and warrior knights" - Sounds like Rule of Threes to me. Don't let yourself be constrained to only putting nouns in a series of threes; many writers are drawn to do so, as it is common in public speaking. As a general rule, when distinguishing anything either with adjectives or a noun series, be sure that all of those nouns contribute something that is not already implied in the series or in the connotation of the noun. 

9. "warrior knights" - What follows is definitely my own preference: one should not attempt to make a piece of writing sound like a DnD game or any other RPG by using RPG terminology. The use of that terminology limits the flexibility of the words. An assassin ought to be someone paid to kill someone else, not a man in tight black leather wielding knives with a scruffy voice. There is an entire subculture that uses these words and phrases in these specific ways, and if one continues to use these words in such a manner in her personal work, then her writing is homogenized with the rest of that subculture. It may be useful to refer to a kind of person with a specific set of perks, traits, and mechanics in an RPG, but it makes an independent piece of writing dull. You'll be unable to distinguish yourself, and your writing will sound bland and passe. You don't have to attempt to be completely original from anything ever written (as opponents of this criticism will attempt to imply), but it only hurts a writer to sound too much like other writers. You are a frequent GM and tabletop player; be wary of falling into this trap. All of that is what I derive from the phrase "warrior knights." I'd advise sticking with knights. 

10. "as just happened" - Unnecessary. The reader knows this happened. You told them. Let "send a door barreling over itself" stand on its own; the readers will understand. Let them make the connection; allowing the reader to make leaps and pick up on the implications themselves makes the piece intellectually stimulating. See "show, don't tell." 

11. "in this" - Very informal language. Change to "Baxter was only present..." 

12. "He grinned...innocent, shining eyes" - you're jamming a lot into this sentence, and it feels awkward. Don't be afraid to use short sentences or cut back. 

13. "innocent, shining eyes" - A very common descriptor for eyes. One seldom doesn't use some adjective regarding light when describing eyes. Remove shining. Consider removing the mention of his eyes altogether. He is a child, therefore innocent (or innocent seeming; see [i]Lord of the Flies[/i]), making the description of the eyes almost pointless. One often mentions eyes when introducing characters anyway. 

14. "two handed claymore greatsword" - Are there claymores that are one handed? Are there claymores that are not greatswords? If no to both, then do not bother distinguishing. Ineffectual attempts to distinguish cause the opposite effect: they blur the image rather than sharpen it in the reader's attempt to think of a two handed claymore greatsword that is different from their image of a claymore. 

15. "all at once" - Is it possible to be fat, muscular, and tall at different times? Are there those that change between the three, picking and choosing which of them they want to be today? 

16. "exactly fit / actually standing" - "Exactly" may be redundant here; I'm almost certain "actually" is. As opposed to figuratively standing?

17. "homeowning" - Redundant with "of the house." It may be possible that he's only living in a home that belongs to someone else, but unless stated otherwise, the opposite is implied. 

18. "of a risque nature" - Consider changing to "risque literature." 

19. "very similar" - What's the difference between "similar" and "very similar"? The difference is clear in theory, but not in practice. I cannot imagine what two sets of hair look like when they are very similar instead of just similar; the image is the same. Applies to many uses of "very." 

20. "As for the brash one that kicked down the door?" - Rhetorical questions are often poor ideas, unless you intend your narrator to actually be a character. As your all purpose, omniscient narrator, they do little besides be informal. 

21. "or LJ for short" - Personal decision, but remove, unless your narrator is a character. These characters will no doubt talk to each other; you can use that to introduce the nickname. 

22. "eager energy" - Energy is rarely not eager. Is there reluctant energy? Lethargic energy? 

23. "tilting its head and looking over to the side" - Not important. Reflects the desire to truly be working in a visual medium rather than a literary one; I often feel the same when I'm writing fantasy. Unless he's turning his head to pay attention to something else that's important and about to be described, this serves no purpose. If that were the case, it'd be a great way to introduce something imposing, so much so that a dog recognizes its presence. 

24. "as she sat" - You already told us she's sitting, though if you're attempting to distinguish between the dress' relative length when sitting as opposed to standing, I could see the argument; however, is that an important detail? Preference decision. 

25. "as she... on either side / she waves... clawed at it." - Lots of description and events that I don't know how I feel about. I guess it can stay. It's jammed in. I think I see little significance in describing the sitting position of the girl. It's very distracting. Again, preference decision. [/hider]

I've been doing a lot of this, so I'm going to stop. Take these ideas and apply them everywhere, though remember there are no universal rules to writing. Don't write like it's a movie. Don't write like you speak. Don't write like you're in an RPG. Not every noun needs an adjective, and not every verb needs an adverb. Be precise, and use specific words and creative word/modifier pairings that are evocative rather than using them en masse. I'm also very fallible, so again, grain of salt. 

Keep going :D You can do it.