This Weapon Fusion System is actually known as Weapon Synthesis within the game, but I believe this title makes more sense than the Japanese name.

Weapon Synthesis

武器合成: Weapon Synthesis is a new menu.

Now the Weapon Synthesis system is not the same as Phantasy Star Universe synthing of weapons. In Phantasy Star Universe you would find materials to compose a weapon and hope for the best.

In Phantasy Star Portable 2 Infinity, the weapon is already made, all you can do is increase the elemental attribute percentage of the weapon.

In order to increase this elemental attribute, you must fuse weapons of the same name together. This improves the base weapon’s attribute rate.

• Weapon Synthesis Terminology
  • Base Weapon: This is the original weapon
  • Plus Weapon: Weapons of the same name will fuse with the Base.
  • Fusion Code: This is needed for Weapon Synthesis.

You can only synth weapons of the same name.

The weapon designated as BASE must have an element attached to it. You can’t obviously increase the attribute of a neutral weapon. 

The weapons designated as PLUS can have any attributes attached to it, even neutral. They all must have the same name as the BASE weapon. Yes you can also use Extended weapons as the PLUS weapon, it doesn’t matter if the weapon rank is different. You can fuse up to 10 weapons of the same name and can use 1 fusion code at the same time. (Fusing 2 weapons uses 1 fusion code and fusing 10 weapons uses 1 fusion code. Try to do all your fusions in one go).

When you synth weapons, they will always become successful, there is no failure.

• The rules
  • Base Attribute + Same Attribute below 29% = +2% added
  • Base Attribute + Same Attribute over 30% = +3% added.
  • Base Attribute + Different Attribute = +1% added.

Please be warned, the weapons fused become the base weapons.

Now even though you can fuse weapons of the same name of different weapon rankings, you will lose that S rank weapon, since a part of its attribute rate is added to the base weapon. Any weapons designated as PLUS will be gone after synthesis. So I would rather use the S rank weapon as Base.

You can synth the same weapon over and over but the upper limit is 50%.

You can obtain fusion codes by importing your PSP2 save, but you can obtain more of them by doing Infinity Missions.

[via pspo2iblog]

Password Cards

Steel Heats I Password Card

Skia Blade I Password Card

So you can obtain these password cards if you attend some play events throughout January 15th to February 19th, 2011.

But wait, “Didn’t you say Hyuga’s weapon was a product code?” Yes we thought so, here’s why…

Using the fill in the blanks, Terada posted Hyuga’s Weapon’s'  “_ _ _ _ _ _ー_” 

Using the Katakana for Product Code fits the spaces, and so 2ch came into agreement. But then out of nowhere on the same day, Rapico tweeted, ヒューガのパスワードカードがもらえるですとぉ～！！！そんかネタバレで大丈夫か？きゅきゅ. Hyuga’s Password Card, but I guess we didn’t believe her except for one person. 

[via 4gamer]

Fusion Theory

• Base Weapon: 1 Spot Open: Element Only
  • Saber
• Plus Weapon: 10 Spots Open: Any Element
  • Saber
  • Saber
  • Saber
  • Saber
  • Saber
  • Saber
  • Saber
  • Saber
  • Saber
  • Saber

This is text from 2ch:

ベース：炎35％
炎(2)+氷*3(3)+雷(1)+闇(1)=7％
炎42％

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Base: Fire 35%
Plus: Fire (2) + 3xIce (3) + Neutral (1) + Dark (1) = 7%
Result: 42% fire

***

シロクローは炎25％だから、10個あっても20%UP止まりじゃないか
45％あればほくほくだが、

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The  Twin Snowy Claws is 25% Fire, adding  10 of these increase attribute by 20%, becoming 45%.

***

つまり俺のサイコ土1、1、2、4、5、11、17を合成すれば土41に？
それはちょっと嬉しい

> Reply
17+2*6＝29
になるな
誰得

***

“So if i had Psycho Wands (Ground) with the values of: 1,1,2, 4, 5, 11, 17; Would it become 41% Ground? I’d be glad if that were the case.”

> Reply

“It is 17 + 2*6= 29″

(Using 17% Pyscho Wand as the base, the rest of the 6 Psycho wands who all have the same element will add a total of 12 to the base Psycho Wand. That means after composition the Psycho Wand will become 29%)

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虹レア同属性40%二つとか出ても43%にしかならないの？

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If I had two rainbow drops that are 40%, then fuse them, it only comes out 43%?

(When the Base weapon’s attribute matches the Plus weapon’s attribute, and the Plus weapon’s attribute is over 30%, only 3% is added after fusing. 40% Dark Saika (BASE) + 40% Dark Saika (PLUS) = 43% Dark Sakia.