Is the weaponed destroyed or anything?
No, it just gains the attributes of the weapon.
edit: btw it needs to be comboed with another deck since the morning glory is immaterial
Yes, that's the point. Besides, why would you just want to add 8 attack when you could add 8 attack and momentum, or 4 attack and venom, or 6 attack and scramble? Also, note that you don't have to use weapons of your own in order to use this card. Also, have you seen the recent buffs to the 'other' weapons? Mono light stompy would be amazing with this card.
The fact that this card can be used (and be effective) in any number of elemental combinations makes it quite attractive, IMHO.