So actually it's a better crusrader.
Discord looks more like a sword and arsenic more like a trident with 2 teeth
Well, it's not better, since its ability is limited to daggers. Doing some math, the average stats after endows are: 5 | 4 for the unupped, 6 | 5 for the upped.
It also has the ability, of course, but it needs another card to work, and it must wait a turn to endows (i guess it should wait a turn, like all the abilities in this game)
When i use Crusaders, i try to endow many abilities to deal with different situations. The best of Crusaders is that it can destroy permanents or pillars and lobotomize or rewind creatures.
Rogue | Assassin effects are only "raw firepower" and cannot counter opponent strategy, except for Discord that disrupts opponent's quanta.
I think 4
cost is balanced.