Grieving family and friends said a final goodbye to Douglas Hibbitt, of Buttermere Avenue, Burnham, on Friday, two weeks after the 'determined' lad lost his fight against a type of cancer called rhabdomyosarcoma.
In an emotional tribute, the kickboxer's instructor Justyn Billingham presented the 13-year-old his original black belt at his funeral at All Saints Church in Dedworth.
"He was one of the most loyal and determined students I have had and he would have got the black belt if the cancer hadn't got there first. Of all the people I have ever experienced he had the best warrior heart and warrior spirit because he just kept fighting and fighting.
"It was his dream to get his black belt so I thought it would be a fitting tribute to give him my original belt which means so much to me," said Mr Billingham, owner of Blaze Martial Arts and Douglas' coach for six years.
The Dedworth Middle School pupil died on Thursday, March 29, with his family by his side, a year after he was diagnosed with the disease.
Speaking at their family home this week, the teenager's parents paid tribute to his brave struggle.
Dad Gareth said: "Douglas never slowed down. He was always in high gear even when he could no longer walk or even lift his hands properly. He enjoyed kickboxing. When the cancer occurred he continued grading and then when he wasn't fit enough he started training and then when he couldn't train he start coaching. That was Douglas, that determination."
Mum Brenda said: "As the disease progressed he was always very courageous. He was always laughing and joking and always had a smile on his face. He was a fighter. He didn't want to centre on this disease, but wanted to live his life to the full to the end."
At Christmas, Douglas was among 40 children who attended a festive tea party at No 11 Downing Street attended by celebrities including former Spice Girl Geri Halliwell.
Moving tributes have been posted on the teenager's Facebook page and left outside his school in Smiths Lane, Windsor.
Stuart Muir, headteacher at Dedworth Middle School, said: "We should remember that Douglas was a fine young man. He was incredibly courageous, witty and hard-working, always smiling and always willing to help others and a real credit to both his family and the school. He will be solely missed."