Texas Penal code is pretty clear on this.. See below.. I have highlighted the last line in red for you... I would suggest however that you look over this link for the Texas LTC-16 as it relates to Texas License to carry handgun laws.
https://www.dps.texas.gov/InternetForms ... LTC-16.pdf
Scroll down to around page 53 or so until you get to PC section 9. Here you will find all of the verbiage related to use of force and deadly force...
Fortunately or unfortunately Texas law isn't always Black and white... There are multiple variables that always need to be considered. Time of day. Location, and so forth. If you are say a young woman and you have found yourself surrounded by a group of very intimidating men who are threatening to rape and or murder you then you are going to have much better leeway in the use of force or showing of force.. I doubt to many juries would find you guilty (personal opinion)... As others have said, your best course is to A. Try to de-esclate the situation and B. Attempt to remove yourself as quickly as possible.
With all of this being said, now that Texas is open carry (with LTC), there really isn't any major laws against moving your shirt around to show that you are armed.. I'm not going to lie and tell you that in certain situations I wouldn't do the same thing... However as soon as you put your hand on your weapon and or remove it from the holster you have now escalated the situation and could be an illegal use of force...
Sec. 9.31. SELF-DEFENSE.
(a) Except as provided in Subsection (b), a person is justified in using force against another when and to the degree the actor reasonably believes the force is immediately necessary to protect the actor against the other's use or attempted use of unlawful force. The actor's belief that the force was immediately necessary as described by this subsection is presumed to be reasonable if the actor:
(1) knew or had reason to believe that the person against whom the force was used:
(A) unlawfully and with force entered, or was attempting to enter unlawfully and with force, the actor's occupied habitation, vehicle, or place of business or employment;
(B) unlawfully and with force removed, or was attempting to remove unlawfully and with force, the actor from the actor's habitation, vehicle, or place of business or employment; or
(C) was committing or attempting to commit aggravated kidnapping, murder, sexual assault, aggravated sexual assault, robbery, or aggravated robbery;
(2) did not provoke the person against whom the force was used; and
(3) was not otherwise engaged in criminal activity, other than a Class C misdemeanor that is a violation of a law or ordinance regulating traffic at the time the force was used.
(b) The use of force against another is not justified:
(1) in response to verbal provocation alone;