Eh. I do think that Warrior needs a little bit of a rework as it is purely stats with no other redeeming qualities. However, the stats it gives are really strong for those who would want to use it. CDR AD and Armor Pen are everything that early pressure AD junglers need to succeed.
I don't think you should buff the item as is, like you described. It's an item that doesn't scale yes, but the champions that traditionally build it aren't meant to scale. With champions like Vi, J4, Lee Sin, and Pantheon being some of the primary users of the item, they want an item that is going to give them as much power early as possible, and the current warrior does this fairly well (particularly after the buff it's getting with the revert of its AD). The thing about scaling items is that they have to be gated by being weaker early in the game. Devourer and old Cinderhulk were cases of those lategame centered items. With Cinderhulks power shift, it joins Runeglaive in being a midgame centered item with some early power (they are kinda strong when you first buy them, but they scale when buying more of one stat, but not very hard).
Warrior is a different beast and I think it should be. The users of Warrior are all about early-midgame and they want the power in the item when they buy it. The current warrior accomplishes this fairly well as it is loaded with cheap AD, CDR, and Armor Pen, so champions who buy it get the power to enhance their early power instead of an item that will lessen their fall-off come lategame. If the item maintained that early powerspike, but then gave more stats later in the game, it would be an item that was just overloaded.
There was a version of Warrior that was on the PBE a while back, and it was very close to the old Spirit of the Elder Lizard and applied a true damage DOT on the enemy you hit with basic attacks or physical damage abilities. It was probably found to be too strong and was taken out of the game as the DOT scaled off of the Damage you dealt, which was an incentive to get the item on really high base damage champions (Lee Sin) and simply dominate. I think the item was in the right direction though and I think that we will see more iterations of Warrior in the future. The item had 40 AD, 10 CDR, 0 armor Pen and then had the true damage DOT. This could still be implemented but I think it needs to be based more on Total or Bonus AD rather than simply damage. An issue with this though might be that laners such as Zed, Talon, and other AD's might pick it up and abuse it as they amass AD rather than getting 1-2 AD items and then building defensively so this too would be hard to balance. Giving it a higher base DOT and then lowering the AD scaling might be a way to go, but I would also adjust that the damage could only be applied on Basic Attacks and that it would do more damage to monsters than champions (like how Runeglaive and Cinderhulk work).
I'm not sure ultimately if this is the correct way to go (DOT Warrior), but it would scale better than the current warrior and would feel like less of a waste come lategame. It might have to take a hit in the early game with losing it's armor pen but Brutalizer was a kinda crappy item to build from anyway as the difference between Warrior and Brut + Smite upgrade was about 60 gold so you usually wouldn't have brutalizer in your item inventory anyway as a jungler unless you skipped your upgrade. It could instead build out of double longsword or a pickaxe and have a smoother build path.
-Scales with AP the more AP you get the more damage you deal
-Scales with HP The more HP you get the more Tankier you get
-Scales into late game with the double proc of its own base magic damage and any other on hit items (Btrk/nashoor tooth/etc)
which pretty much dosent scale to anything after 20 minutes....
^^ Why would you ever get this item
