I have just a couple of important changes to suggest that add to what has already been corrected nicely by Tom. They are in the first sentence, which as your introduction may be the most important one.

The gothic shield was born in the XII century, it is the oldest that we have.

The Gothic shield was created in the 12th century, and is the oldest still in existence. 

Here's why:

  - "Gothic" is a proper noun, derived from the Goths, and needs to be capitalized.

  - Shields aren't "born". That word is used for living creatures and for some abstract things, like ideas, but isn't used for other physical things.

  - We typically don't use Roman numerals for centuries, preferring to use a standard ordinal number.

  - Your version has joined two complete sentences with a comma. This is called a "run-on sentence" and needs to be fixed by either adding a conjunction like "and" as I have done, or by ending the first sentence with a period and starting again with a capital letter.

  - "The oldest we have" suggests that someone else might have one that is older. I don't think this is what you mean. I think you mean the oldest that anyone has, so "the oldest in existence."

One other little change: "everyday" in the following sentence is an adjective, and is written as one word when used in this way.


Yellow being used as warning signal, in every day life: before traffic light red, we have yellow, school bus is yellow, in the auto racing yellow flag means danger.

Trechware: a graphic logo explanation

LOGO EXPLANATION

The gothic shield was born in the XII century, it is the oldest in existence.
It is a classic sign of protection and it was worn by soldiers during times of war.
Today, trecnchware’s??? engineers are fighting a different type of war.
Their war is against cyber attackers who threaten our intellectual property.
The shield itself contains two letters: T and W.
The first is formed by the cross used to draw the shield, while the second is formed by the three coloured triangles.

COLOR

Yellow is used as a warning signal in every day life: before the red traffic light, we have a yellow light , school buses are yellow, in auto racing a yellow flag means danger.
The yellow shield is designed to transmit a feeling of protection against real danger.

TEXT

The two words Trench and Ware are written in the same font, ROBOTO by Big G (open source), but they are different because we have two styles.

Trechware: a graphic logo explanation

LOGO EXPLANATION

The gothic shield was born in the XII century, it is the oldest that we have.
It is a classic sign of protection and it was wearing worn by soldiers in war.
Today, tTrecnchware’s engineers are fighting a different war.
Their war is against cyber attackers who threaten our intellectual property.
The shield contain in itself two letters: T and W.
The first is formed by the cross used to draw the shield, while the second is formed by the three coloured triangles.

COLOR

Yellow being used as warning signal, in every day life: before traffic light is red, we have yellow, a school bus is yellow, in the auto racing a yellow flag means danger.
The yellow shield would like to transmit a protection feeling without denying a real danger.

TEXT

The two words Trench and Ware are joined by the same font, ROBOTO by Big G (open source) and in the meantime they are different because we have two styles.