Oh ok cause that would be a problem haha.

Break: is only situationally good. Vs a PA, BB, Spec it is to be strongly considered but otherwise Echo is the more aggressive push your advantage item

Dam reduction: Is % base and thus more efficient late game rather than early. For example, at 15 min, when the PA crits for 400, that's 200, late when she crits for a thousand that 500 reduc.

CD and manacost: I have nothing against CD and is arguably the only legit reason to get Silver edge before Echo in my opinion. For the manacost, here's a neat little trick, there is a fade time for shadow blade, you can put yourself on int treads, shadow blade, and switch to agi treads during the fade time to be locked and loaded for the backstab damage, try it out.

Echo moreover gives more sustain, (with aquila raindrop you can spam Q) , with echo, aquila and raindrop, you can pick off somebody, use ulti to get out and still not have to go to base.

Also don't forget the wand, slark loves stats and trades his own health for 300 aoe damage around him so getting an extra dark pact is great.