You're right, but I don't think it would be fair for an assasin to have an award that can only be achieved by buying an item while generals can achieve all the awards using only their own skills. Besides, I doubt Universal Gadget can compete with bramble shield, heal, and the like.
If sedna is taking awards for dmg/kills/buildings/etc from you, you're playing this game wrong.
It's pretty straightforward to me. Ask yourself this: If you don't buy the healing spell on sedna, and focus on the pounce dmg ability, does sedna compare dmg wise to other generals? Not really, no. Sedna's potential is nowhere near some of the other DG's dmg wise. This is because There are Dmg dealer demigods, and there are support demigods. Yet there are only dmg dealer awards. Put some support awards in, or make it so healing counts for assists, or something.
There are a couple decent ideas in this thread..
"Allow Favor tips, or MVP voting" -- At the end of the game, you're team votes on who is the MVP on the team. If sedna/support demigod is doing their job, many times throughout the battle sedna/supportDG saved the day, allowing the other members of the team to stay in the thick of it, and win.
"Make a support award" -- Just like Sedna shouldn't win a DMG award if Sedna's teammates are skilled, the DMG DG's shouldn't be winning a healing/support award, if sedna's trying to do that either. Some people will note that without an item it wouldn't be possible for the DMG DG's to win the support award. I don't agree. The support award would cover all aspects of saving teammates. For example, if you are torchbearer, and regulus is retreating, but not fast enough, and will die, and you freeze everyone.. you just saved regulus.. I.e. If another player is recieving dmg, and you do something to prevent that player from dying, then that's supporting.. That could apply to Rook's Roll, etc.. The idea would be that if you use your stun or sheild on an opponent who is dmg'ing a teamate, and that teammate survives (more than 20(?) seconds), than you get a support credit. This means that in an all Assassin game, there would be still some competition for that support award. Good timing of skill use/smart play would be rewarded.
Of course, Sedna/QoT/Oak are likely to win this award, but again, that's not any different from Regulus likely to win the building destruction one, or another Dmg Focused DG winning a DMG award.