The Anglo-Saxons, better known as the English, were originally named after the knives they carried. These were the "Saxe", which incidentally still means "knife" in modern North German dialect, North Germany being where the ancestors of the English came from. So, the "Saxons" translates into modern English as the "knife-men"
The Saxe was about 16" overall, with an 12-13" blade, which ended in what we would now call a "gut hook". Except that it was highly sharpened, and was in fact a "ripping-hook". The obvious purpose was to rip open their opponents in combat.
Their proverbial ancestor was named "Saxe-noth", which means "knife-daring". Presumably this was the nickname of one of their real ancestors, renowned for his exploits with this kind of knife.
The "Saxe" was the Saxons' "trademark", and, indeed, part of their pagan religion.
Every, and I do mean every, Saxon man, woman or child was buried with a knife. Even small children were buried with knives that they wouldn't have been able to use for another 4-5 years had they lived. The Saxons saw to it that their dead would not be defenseless in the next world, as the English (their descendents) saying goes: "you never know"...
The Saxons converted to Christianity from their pagan religion soon after they came to England, and by 700 or 800 AD, they were sending missionaries to convert their cousins back in Germany. As Christians, they no longer followed the old customs mentioned above quite as much.
Scientists believe that the Celts had their origin in a valley on the southwestern slopes of the Alps, near the southeast border of France. From there they spread out to many parts of Europe and the Near East, and in modern times, to the rest of the world.
The modern branches are, starting from the South, the Britons of Northeastern France in Brittany, the Cornish in the southwest corner of England, the Welsh in Wales (Western England), the Irish (no longer British, but see below), and the Scots (whose ancestors mostly came from Northern Ireland). In the Near East, the Galatians mentioned in the Bible, to whom St. Paul wrote that "whatever a man soweth, that shall he reap", were Celts who had immigrated there. A local king induced 20,000 of them to settle there as soldiers in his army and traders back in 200 BC with grants of land and money.
Celt means something like "free warrior". Celts were known in ancient times for their cleverness and bravery.
Celts attacked and looted Rome in early days when it was just another small Italian city, before it became the center of the Roman Empire. They extracted a very high price in gold as well. The Romans got the gold back with interest a few hundred years later, when Julius Caesar conquered the Celts, and extracted their large supplies of gold from them through the tribute and taxes he and his successors made them pay.
The Celts were also the "Metal Masters" of the Ancient World. Metalworking was their specialty, and all who could afford it bought their blades from them. This included the Roman Army, whose swords were made by a branch of the Celts in Spain at that time, and imported by the Romans.
Germans were then far behind in all of this, and could manage to make a spear point or knife if it wasn't too big, but swords were rare among them and very highly prized. These were made by the Celts as one of their specialties. The sword was usually leaf-shaped, and examples can be seen in reproductions offered on the web, like the "Sting" sword of The Lord of the Rings.
The fight between Germans and Celts began with the Saxon migration to England from 500 AD to 650 AD. They were joined by their neighbors the Angles and the Jutes (from Jutland, now in Denmark), and were known in general as Anglo Saxons, as they are today. They pushed the Celts out of Eastern and Southern England, so that they remained on the Western and Northern borders: Cornwall, Wales, Ireland, and Scotland, where they mostly are today.
On the other hand, the German and Celtic nobility considered themselves equal, and developed family ties over the centuries.
Later, about 500 years ago, many Celts migrated to England to share in the prosperity that would later lead to the British Empire.
So both at the noble level as well as the common level, especially in the larger towns and cities, the English are partly German and partly Celtic. After Ireland became independent, and so were no longer British, the Celtic population of England still remained there, while the Irish and most of the other Celts, over the centuries, had adopted English customs, standards, and language, and so became almost exactly like the English.