This card is very helpful in a Beatdown Deck, as it has 2400 ATK while remaining Level 5.
A good card to discard for the effect of "Armed Dragon LV5" is "Roc from the Valley of Haze" because most commonly used monsters have an attack of 2400. Plus Roc from the Valley of Haze returns back into the deck when discarded so it can be re-used again and again.
Any cards that can help with this dragon, such as "Burden of the Mighty", so this card can destroy any kind of monster with your bad hand.
If the trap card "Light of Intervention" escapes you, try using the spell card "Dark-Piercing Light" to flip all monsters your opponent controls face up during Main Phase 1. While you risk the chance of flipping something such as a "Man-Eater Bug" or "Hane-Hane" face up, you can use the effect of "Armed Dragon LV5" given a good hand, and then directly attack for 2400.