This is the content of the refusal letter I received:
I have refused your application for visit because I am not satisfied that you meet the requirements of Paragraph 4 Appendix V: Immigration rules for visitors. I have considered your application in context of evidenced personal circumstances and funding.
You have declared in your visa application form that you are financially supported by spouse/partner/other. You state that you propose to visit [the] UK to try and enlist in [the] British Army. You have further stated that you and your sponsor will meet the costs of your proposed visit.
I must consider the evidence of your personal circumstances and funds as demonstrated by you. You have stated you are financially supported by spouse/partner/other. However, you have provided no evidence relating to your circumstances in Ghana other than a copy of an school ID card from Takoradi Polytechnic which expired in July 2016.
You have stated that your sponsor will help you pay [for the] proposed visit and will give you £1000. You have submitted a letter of support from Jeffrey Owusu who states he is your cousin. However, whilst you have submitted evidence of his financial circumstances, you have submitted insufficient evidence to demonstrate your relationship to him to assure me that his proposed third party financial sponsorship is reliable.
I am not satisfied that you have sufficiently demonstrated your personal circumstances and funds or that they re such that you can be relied upon to meet the condition of visit entry clearance.
Taking above into account, I am not satisfied that you intend to leave the UK should your application to join the British army be unsuccessful. Furthermore, I am not satisfied that you have sufficient funds available to cover your costs whilst in the UK without working or accessing public funds. Your application has therefore been refused under Paragraph V4.2 A and E.
Future applications. Any further UK visa application you make will be considered on their individual merits. However, you are likely to be refused unless the circumstances of your application change. In relation to this decision, there is no right of appeal or right to administrative review.