Overall good attempt. Atleast you tried.

The essay is about military engagements by UN, not the role of UN in military conflicts.

Try to develop arguments from different angles.

Give solid arguments with examples. How P5 will allow a change in SC. One veto exercise more power than other 192 votes.

In essay section, a link was shared yesterday. Go through that document.

You have almost cracked half topic and just need arguments and more analysis and angles.

Correct interpretation of topic and solid arguments supported by facts are pre-requisites. Other things such as "beautiful English", excellent expression, quotations, etc. are secondary.