"Hardened Armed Dragon" is not part of the archetype due to its Japanese name, 「ハードアームドラゴン」, not containing 「アームド・ドラゴン」.
In the Yu-Gi-Oh! GX anime, Chazz obtains these cards while at North Academy, shortly after obtaining "Ojama Yellow, and uses them throughout many of his further appearances throughout the series.
The original "Armed Dragon" series focused on sending cards from the hand to the Graveyard to destroy monsters on the field. Depending on the ATK of the monster sent, certain monsters could be destroyed while others were not. This is why cards that decrease your opponent's monsters attack, such as "Shrink" and "Burden of the Mighty" can be helpful. "Armed Dragon LV10", being the strongest, simply destroys all face-up monsters regardless of their ATK and any card could be sent from the hand to the Graveyard, rather than only monsters, as was the case with the lesser forms. This series is one of two "LV" Dragon series (the other being the "Horus the Black Flame Dragon" archetype).