This is true. However, the Arsenic brought in poison, something which is highly underestimated by a lot of players. (Although also overestimated by a lot of players)
The problem is: poison is good only in longer matches where your "Main damage" is blocked by shields/sundials/whatever.. However with this deck this isn't a problem I found; when the game becomes longer you will get enough cc to keep annoying creatures (maxwells/ultiharid/dragons etc) at bay. You shards can almost always remove all shields, meaning the poison is simply "extra damage" - as if the weapon would deal more damage.
I found direct damage through flesh recluse (which starts at 6 more dmg) + 2 more dmg from vampiric stilleto means that this combo deals more damage early/in a rush scenario than graviton fireeater + arsenic. Arsenic has to be up for 4 turns before 'beating' vampiric stilleto. Graviton fireeater has to be up for at least 5 turns before giving enough damage as flesh recluse... + at least 4 fire quanta in that case. (Which is a lot considering you can also want to use rage elixer).
And as I said: after those 5 turns your sofo shield should be up, you should be able to stop the shields and you should win.
+ When I tested the deck I discovered I almost never could play the fire eater anyways, there's always a sofo, or oyugh (ability) waiting to be used instead.
Ow I should say: I'm also using an upped forest spectre instead of unupped. Found the 1 less turn to be in cc range very useful - as without graviton fire eater the forest spectre will be the main dmg source lategame.