Cause of abbreviations on Yu-gi-oh! cards
As strange as it sometimes comes through, Yu-Gi-Oh! Cards are commonly being censored for the western market, not only visually, but also in text. One prominent example is the renaming of "Magic Cards" to "Spell Cards" shortly after the release of the third set "Magic Ruler", which was released as "Spell Ruler" in Europe. This renaming is probably due to Wizards of the Coast complaining about the similarity to their own game's name ("Magic the Gathering") and possibly even threatening legal action.

Notably, Konami was very strict in removing sexual, cultural, religious and political references as much as possible, but also several cases of copyright driven censoring (like the Magic thing mentioned above). Examples include 


Premature Burial, Injection Fairy Lily or The Cheerful Coffin (the originals had cross symbols in their pictures, religious reference),
Sangan (who was originally called "Critter", which was too close to the unrelated "Critters" franchise/brand),
Tragedy (the original showed a Guillotine, which refers to European and notably French history as a symbol of the cruelty during the French Revolution) as well as
countless girlish characters whose clothes and bodily features were "adjusted" (most well-known example for this is Dark Magician Girl).


There are many, many more examples.

As for your examples:


Lord of Dragons doesn't seem to be offensive, so it's either a copyright thing (there are several "Dragon Lord" brands in gaming and entertainment) or one of the few cases where the name was already abbreviated in the OCG for style reasons. @Discord's guess is actually not that far off, avoiding the reference to the Dragon-type might actually have been a reason so as not to confuse the children this game was targeted at.
Red-Eyes B. Dragon is interestingly the only one (well, the only family) where they did it by abbreviating, but the word Black was entirely stripped from Yu-Gi-Oh!. I have no idea why they did this, but up to this day, nearly every single instance of the word Black has been categorically censored. Dark Magician, Dark Hole, Dark Magician Girl, Dark Magician of Chaos and many more all had the Black instead of the Dark when they were first released in Japan. Some of Red-Eyes' cousins share the transition to "Dark" (Red-Eyes Darkness (Metal) Dragon), some don't (Red-Eyes B. Chick). As far as I know, the only exceptions to the Black censorship are all objects without soul (such as Pitch-Black Power Stone), which supports the theory that this censorship is intended to avoid references to skin colour (as pointed out by @SQB).
The A. Forces, as has been noted by @ire_and_curses, is a reference to the Allied Forces, which is a term used to describe Germany's enemies during World War II (specifically, the USA, the UK, France and Russia), who ended up winning the war and dividing Germany, leading to a long history of cultural, economical and political tension known as the Cold War. The term has also been used in other military contexts, but always in conjunction with war.