Byrne, who had demonstrated her great speed, footwork and awareness of space throughout the day to score a host of tries, added a few more to her total in the final.
St Louis, who were denied the influential Kate Hegarty for the final, battled on bravely and registered a score of their own through great work by the excellent Caoimhe Bermingham and the elusive Shannon Geraghty.
Strong attackers, such as Stacey Flood, kept asking questions of the High School defence and were only kept at bay by a huge defensive effort, with Elizabeth Gageby and Abigail Donnelly, in particular, to the fore.
In the plate final, Muckross overcame Sion Hill in a very tight game. Led by captain Claire Cashman, Muckross's ever-excellent Orla Murray opened the scoring running the full length of the field for a stunning try.
Despite missing the big carrying Catriona Barry in the final, Muckross started to exert their influence with some strong running in the midfield from Ashling McCann.
Sion Hill, who improved throughout the day, were certainly not letting Muckross have it their own way, with captain Barbara Mullins and Joanne Cosgrave leading the charge.
Some excellent around-the-ankles tackling from Katie McGowan kept willing Sion Hill attackers such as Shannon Sullivan and Orna Phelan at bay, and Muckross eventually ran out 12-7 winners.
The Player of the Tournament was a hotly contested award with some outstanding displays for all teams on the day. However, the referees and coaches decided that Emma Murphy from The High School was the consistently excellent player throughout the tournament and was fully deserving of the award.
George Ross from Jones Lang LaSalle was on hand to present the trophies afterwards: "Jones Lang LaSalle are delighted to be working with Railway in establishing a programme to goes into schools in our community to introduce rugby to girls who may not have ever considered the sport.
" We are excited to support an initiative that looks to promote women in sport and in what could be the first step for some of the girls in this programme to make Rio 2016 or beyond," said Ross.
Railway's Director of Women's Rugby Shirley Corcoran said she was amazed at the talent on display for all the schools:
"We knew we had some skilful teams and players from our time coaching in the schools," said Corcoran, "but we were bowled away today by the talent, enthusiasm and ability displayed by the girls in a competitive environment.
"I'd like to thank and congratulate all the teams for taking part, their schools and teachers for championing it, and to their parents who supported on the day."
Railway's Mere Baker, who devised and led the programme in the schools, said that she believed that some of the girls could achieve Irish and Olympian honours if they chose to focus on the sport.
"The level and potential of these girls would compare with anything I've seen anywhere in the world at this age grade and development," said Baker.
"These girls will be nineteen at the Olympics in 2016 and with the right coaching, development path, and dedication on their part, I am 100% certain some of them can make it to Rio as Irish Sevens players."
Related Links -
Rio 2016 - Have you got what it takes? - Women's Sevens Screening Camps