Man, I get that “Spiked Arms” is not actually a bug if you keep in mind the spelling but it beats the purpose of the weapon completely. Have you ever seen it in use by any Warrior in Duels mode, ever? There’s so many unused treasures, and even hero powers - completely left forgotten. They are harder to pull off successfully and even then - there’s something in the game that completely ruins it. Samuro, which was one of the main frenzy cards of the expansion, is actually worse with the weapon. It always deals 1 dmg when played and there’s no way around it, it can’t be buffed on board like it normally can be. The weapon is basically a one-time Fiery War Axe (3-2 which is a common warrior card), only works if your whole deck is based around it and after you use 2 charges, you basically lose the ability to use the weapon of any kind for the rest of the game to keep it’s effect in tact. Which is clearly made for frenzy-like minion effects, you can’t really have any divine shield minions and the fact that it doesn’t work with the key frenzy cards is really triggering… I think changes like this are required for the health of the game.
same goes with “Humble Blessings” (just this one is clearly a bug) - for 4 mana you make all your minions cost 3 mana that become 3/3. It’s obviously not a good deal with a regular deck, for 4 mana you make all your minions have less stats than it should be for the cost. So, once again, you have to build your whole deck around it. And if your whole deck is based around one card, and your deck size gets really big in duels really quick - you must have other ways to draw that one card that your WHOLE deck is based on… Knight of Anointment helps with that after you get rid of all the other holy cards that might be useful (once again, making sacrifices). When your deck size gets to 40+ even those 2 cards are usually not frequent enough. Sometimes “Knight of Anointment” gets offered with other cards that might have synergy with the deck like “Invigorating Sermon” which would make sense to take. But if you take it - that’s it, you’re screwed. And sometimes in all 3 buckets there’s a holy spell involved that also instantly ruins the deck since Knight of Anointment can no longer draw the treasure card.
There are also many inconsistencies. I have no idea if this is fixed already or not but I had a run previously with various 8/8 Giant cards in the deck. Most of them were Flesh Giants. I’ve got offered “Scepter of Summoning” treasure (“Your minions that cost (5) or more cost (5)”) and instantly took it - what better synergetic treasure would I want, right? Well, turns out it completely ruined my Flesh Giants. They would stay on 5 cost no matter how many times my hero would heal or take damage - it could be 20 times and they would still stay on 5 mana. Yet if I had 5 cards in my hand I could summon Mountain Giant for free. Which one is a bug?
Apart from these (and quite a few more) I think duels mode could use a little bit of love. So many little changes could make the mode such a great experience… For example, reintroducing bartender Bob every few rounds (like it originally was in adventure runs), making it possible to remove a card(s) that could be ruining your deck. Or perhaps even slightly buffing something.
Personally I think offering cards one by one after the match (until 3) would also be so much healthier. Sometimes 2 of 3 buckets are completely identical, if unlucky - both involving a dead card (for example, with Shaman “cannot overload” hero power a Snowfury Giant is sometimes offered in 2 buckets - a card that costs 11 mana and it’s mana cost can’t be reduced, making it impossible to play even with a coin).
The mode has such a nice potential, everybody loved those adventure runs… But it’s really going sideways - there’s like 3 decks and everyone is playing them with high consistency. Same treasures, same hero powers, same starting decks. And the fact that if you try to play anything else you soon get disappointed by hero powers/treasures not working the way they are supposed to is really the main reason the mode is dying, in my opinion. There are, of course, many other ways that people are suggesting how to revive the mode that SOUNDS SO FUN on the paper to actually reach it’s potential… Why is it so abandoned by the developers? 
sorry for the long post