I like the concept, but the slavery part is terrible, and your post makes me think you don't know much about sword rushing. Also, your swords are weaker than they need to be, and if you ever have to sacrifice either HP or Attack on them, it should *always* be attack that is sacrificed.
is because you wanna rush with alot of swords very early, metullurgy allows you to convert your 100 gold into iron. So instead of making only 4 swords, you make 7-8 swords
Correct about what metallurgy does, although it doesn't convert one resource into the other technically, it does let you spend them interchangeably, which is functionally the same thing. One thing to note at this point is you should have two variants of this civilization, one with iron mining and one with gold mining. Depending on what's more favorable map-wise, pick a different pick whatever variant is most appropriate.
However, you don't make 4 swords at the start of a good sword rush. In a good sword rush, you've made 3 barracks, and sent 12 citizens to mine at the start. You make 3 swords, then early return your mines (1 cit builds the settles), and make another 3 in the barracks *just* before the first 3 pop out. You continue this and pump swords, etc. First swords you produce, as it is a rush, should immediately be sent to your opponent, i.e. rally them there so no time is wasted.
With that said, metallurgy in a rush should function as follows:
1) It should allow you to be able to mix units of a different metal type (iron or gold) to what you're primarily mining earlier than anyone else. In your case, this would be a prophet. (Some surprise or gimmick that enables you to gain an advantage or force a win)
2) It should allow you earlier upgrades than someone using a standard civilization, as you do not need the boosted resources to help supplement sword production. (A bit more threat early on)
3) It allows you to pick the set of mines which is most ideal, gold, or iron, as it doesn't matter what you pick as long as you have 2 civilization variants for each circumstance. (More defendable)
Notice how queuing up more units than normal isn't listed there, because there's really no point in it if you're capable of pumping units easily without metallurgy anyway, and since you are...
since you are rushing, if your rush is succesful, your slavery will award you. Everytime you kill an opponents citizens, you gain 1 citizens from your capitol.
Don't advocate the use of Slavery if you don't know what it does. You know you get citizens, but you have no idea how many you get. Look at the table below and you'll hopefully be able to see why slavery is crap for the cost, ESPECIALLY in a double power civilization where it's costing you 25 civilization points.
Killed-Gained
1-1
3-2
6-3
10-4
15-5
21-6
28-7
36-8
45-9
55-10
66-11
76-12
91-13
105-14
120-15
136-16
153-17
171-18
190-19
210-20
As for Slavery awarding you, you're entirely correct. However, crippling your opponent is a reward in its self--you don't need to use Slavery to make it a reward. More importantly, the CONDITIONAL and quickly diminishing reward you get for Slavery is not worth sacrificing the UNCONDITIONAL rewards you get for spending that 25 points on better things, it's not even worth it when you'll get fairly good returns from Slavery (at least, not in a real game versus any/all good players--slavery has its place in the noobstomp because it's a great way to inflate your statistics).
To make this civilization much more threatening, I'd drop slavery for building cost reduction and sword hit points (and obviously, as mentioned earlier, one with gold one with iron). (You'll need to drop prophet btd too, to fit one of the aforementioned bonuses, I think). The additional massing ability, combined with being able to get a temple a bit earlier (due to reducing wood cost), the stronger swords, and the benefits of building cost reduction later on, would really help out a lot.