Help me !!

I will try to explain where this text comes from.

First go to the ..\Atlantica\Item\Data\ItemTypeTitle.ndt file:

Unique	Name	NameTextNum	Code	ImageFile	ImageFont	GradeCode	IsShow	ItemFunc	FuncParam	TitleTextNum	MakeSkill	MakeSkillLevel	TradeList	bUse	Work	productUnit	Material	Tool	Explain
900	타이틀:용궁지킴이	2109	NULL	10	61	HIGH	1	USE_CHARTITLE	0	4248	0	0	0	1	0	1	NULL	NULL	523
901	타이틀:곰돌이	2110	NULL	10	61	HIGH	1	USE_CHARTITLE	1	4249	0	0	0	1	0	1	NULL	NULL	523

In the table we are interested in 3 columns:
NameTextNum
TitleTextNum
Explain

Now let's try to find these values in the text Manager.
(line numbers to match)
The first file we are interested in is the names of the items.
..\Atlantica\LANG\ENG\TextMgr\TextMgr_Item_ENG.ntx

find in it the lines from column NameTextNum
(In this example, lines 2109 and 2110)

2109	Title: Sea King's Guardian		1st	260
2110	Title: Cubbie		1st	260

Next, we are interested in column TitleTextNum and where to look for the file.
The file is located there in the text Manager:
..\Atlantica\LANG\ENG\TextMgr\TextMgr_TextMgr_ENG. ntx

find in it the lines from column TitleTextNum
(In this example, lines 4248 and 4249)

4248	Sea King's Guardian		1st	269
4249	Cubbie		1st	269

Next, we are interested in column Explain and where to look for the file.
The file is located there in the text Manager:
..\Atlantica\LANG\ENG\TextMgr\TextMgr_ItemHelper_E NG.ntx

find in it the lines from column Explain
(In this example, lines 523)

523

Effect: Increases attack power and defense for 50 mins.

2.3

3154

Both titles have the same effect, so they refer to the same description.

Result:
Variable NameTextNum used to name of the item.
Variable TitleTextNum used to name in the interface window.
Variable Explain used to description of the item when you hover over it.

PS Probably if you change only the text, it is enough to change it on the client side of the game.