May be cleaner as "...discard a card or sacrifice ~". That also gives you the choice to sacrifice it early if you prefer, which probably doesn't matter, but seems only fair and is seen on similar cards.

Given Vulshok Battlegear exists, is this really all that different?

I'm scratching my head... -1 to equip doesn't seem worth the discard, even in a 'graveyard matters set'. If you wanted to 'sell' this rare, it should probably cost . Even then, I'm very against the philosophy of "Make players play with cards they wouldn't want to play with normally by decreasing the casting cost." Unless this card did something specific with the discarded card, I wouldn't do it...

Also compare to Sword of Fire and Ice and the rest of that cycle.

Changed name, and ability to make the card more interesting. still thinking about if i should change the powerlevel.

Oof. Yeah, that feels more like a rare to me. Though, the perfectionist in me wants to change the order of the sentences so that discarding is mentioned first, then the reward is mentioned second. I can see why the other way is appealing as well.

Interesting design but as is, whilst your creatures get bigger, you will seldom want to prevent the damage to the player in favour of more counters (though on a small unblockable creature, you would early) unless you were playing a dedicated mill strategy.

See, this though wouldn't bother me as much. Cards that aren't as powerful as they sound are much better, at least to me, than cards that are powerful but sound bad. I think I could write an essay why, but I'm just gonna say "Weird, huh?"

The thing with this sword is that it can get very powerfull, but it's also a "with great power comes great responsibilty" card. Since i know it takes a while to understand how to play right with it, while some players mills 2-3 turns to much, it can be a loss for them.

And, Why "whenever a card is put into a graveyard" is before the second ability, the reason is that i want it to be the special trigger of the card, and the second ability is just the bonus, so that people read first: Ok, their creature dies, i get a counter, and then, oh? this card combos with itself? that's nice too.

Throw it on a small evasive creature early and use the mill instead of damage option to 'build it up' then transfer to a big hitter and 'Hulk Smash'. Very strong in a mill deck but would be good in a discard deck or even a board clear deck - Wrath of God/Day of Judgement, Armageddon, etc. Nice.

One question though, as worded this would trigger whenever an opponent plays a non-permanent (Sorcery or Instant) as they go to graveyard on resolution. Is that a bit too powerful???

Interesting card. I agree that the power level doesn't seem too bad or too good.

Whenever Wizards print this kind of trigger they say "put into a[n opponent's] graveyard from anywhere" - see Vulturous Zombie. That's probably clearer.