It fits what Mike Mearls said perfectly. A holy avenger IS more powerful and complicated than, say, a vicious weapon, or for that matter, a flaming weapon. The thing does extra damage, raises defenses, is also an implemnt, the weapon is useful to MANY classes (I really wish you guys would stop spewing out 'Paladin' for this weapon ignoring the fact clerics can radiant servant this thing to awesometown).
It's not an artifact... but it's pretty damn meaty with what it can do.
Seriously... 'rare magic items' is not a game rule set in place so that 4th edition's 'the character is the source of power, not the items' can be ignored. It's too central to the game design.
I disagree that it fits what Mike Mearls said perfectly. I cut his article into portions I think contradict your statements, and bolded particularly interesting points.
Dungeons & Dragons Roleplaying Game Official Home Page - Article (Magic Item Rarity)
Magic Item Rarity by Mike Mearls said:
One of the consistent pieces of feedback we’ve received about the Dungeons & Dragons game concerns magic items. Many players and DMs have told us that while plenty of the items in the game are treasures worth risking a character’s life and limb for, the most powerful items felt a little flat.
...
In looking over feedback and inspecting the game, we came to the conclusion that we wanted to add a broader variety of items to the game. A magical sword that unleashes bolts of lightning on command should be able to sit alongside a belt that increases your maximum hit points.
Rare Items
...
Rare items allow us to create a category of treasures that are clearly more powerful without simply forcing them to a higher level of play.
...
By introducing rare items, we can allow those two weapons to sit near each other in terms of level.
So, what does mean if a magic item is rare?
First, the rules assume that the DM hands out one rare item per character per tier. Rare items are meant to be character-defining, powerful objects that help forge the character’s identity in the world. If you find a flame-tongue weapon, you’ve uncovered an important, powerful blade. Since the characters won’t have many of these items, they can be more complicated in terms of type and number of powers.
...
Uncommon Items
The rest of our magic items are now uncommon. They occupy the middle ground between rare and common items. They have powers, but these powers are typically daily abilities. They have static effects, but they are rarely character-defining or critical to a hero’s identity.
...
So first they get feedback that high level items feel a little flat. Then they republish a high level magical item as a rare item. Next, in looking at the feedback they decide to
add a broader variety of magical item. There is nothing added here but a label of "Rare" from the PHB. Rare items let them make powerful items without 'forcing' them to a higher level of play, but lo and behold, the Holy Avenger remains at level 25 and hasn't changed at all or reflected any change in philosophy. We can argue whether we think this item is character defining. But that's purely opinion; a good few people in this thread do get a feeling of 'meh' about it.
That doesn't mean your opinion is wrong, but the majority is something that WotC should be interested in as far as pleasing customers and ultimately making money.
So the uncommon section then says that uncommon items typically have powers, but only
daily (just like Holy Avenger,) and have static effects (+damage) but aren't critical to the heroes identity. We can argue on the second point, but the single power certainly is a daily, which is characteristic, according to the designer, of an uncommon item. As far +1d10 damage being critical to a heroes identity, I mean, maybe, if the heroes identity is damage. And +1d10 is critical to that.
I agree that they aren't going to throw out design philosophies (completely.) But these are items that are completely in the DM's hands that should be interesting plot wise, interesting mechanics wise, breaking new ground, and maybe even being broken power wise. We already have plenty of "meh" magical items. Give us some magical items that are just fun to look at and read in addition to playing with.
If we're "add"ing a new variety of magical item, shouldn't it fall somewhere above what we already had in the Player's Handbook?