salvaging weapon

I have GW Prophecy only and I found out that I can only salvage upgrade rune for weapon if the inscription name has been unlocked (I meant I can only salvage weapon for the unlock inscription regardless what other inscriptions/modifiers exist in the weapon).

Is this common? Is there a way to unlock more inscription or modifier?
Also, how can I see the list of all unlock inscription/modifier/rune/insignia?

Thanks.

Here is the link to the wiki which lists all enhancement items http://wiki.guildwars.com/wiki/Main_Page

As to salvaging, are you using an Expert Salvage Kit?

Yes, I am.

I found couple bows (blue and yellow) and when I tried to salvage it, it always give me the same option to salvage (Lengthens Poison duration on foes by 33%) even though the other bow does not show this in its attribute.

This make me think that only unlocked upgrade component will show up on the salvage option regardless of what the attribute the weapon has (is this correct)?

And also, how can I unlock more upgrade component? how can I view the list of all unlock upgrade component I have so far?

if the 2 bows have poisonous bow strings then u can only salvage poisonous bow strings from them... u cant get a zelous or vamp bow string from an item that doesnt have 1 attatched to it

OK, here are three swords I own.

From #1, I can salvage the Shocking Hilt, Pommel of Swordsmanship and the Inscription.

From #2, I can salvage the Icy Hilt, Pommel of Swordsmanship and Inscription.

From #3, I can salvage the Pommel of Enchanting.

Shocking Long Sword of Swordsmanship
Dmg: 15-22 Req 9
Swordsmanship 19%
Inscrip: +15% vs hexed
----------

Icy Bramble Blade of Swordsmanship
Dmg: 15-22 Req 9
Swordsmanship 20%
Inscrip: +15% vs hexed
-------

Jade Sword of Enchanting
Dmg: 15-22 Req 10
Dmg: 15^50
Enchantments last 19% longer

When you click on an item to be salvaged, a window opens showing what can be salvaged from it.

As I select, if I have never salvaged that particular upgrade before, a notice will open on the screen saying it has been unlocked for my account. That means the I would get the notice for both Swordsmanship Pommels as one is 19% and one is 20%. The same thing happens if you salvage an inscription.

The Jade sword has an inherent mod instead of an inscription, so that cannot be salvaged.

http://wiki.guildwars.com/wiki/Salvage