I had a go at the spring balance thinng at Newark Fly Fair a couple of years ago. Mick Bell was running a comp to win one of his new #12s....the person who pulled the balance round to the highest lbage won the rod. One hand on rod and one hand on line was the rule. The balance was attached to a big block of concrete with an eye cast in it. Carl was crouching down to read the balance.
I got my go and bent the rod over to the point where the fly line broke - it was a 30lb line, so they gave me 30lbs as my result. i was astounded, the rod tip sprang up past Carl's face about an inch from his eye! It was a close call.
Anyway, i didn't win the rod becasue numpty came along half an hour later an dused two hands on the rod, one ahead of the grip and promptly broke the rod by causing a hard spot - the line didn't break.
When playing abig pike I do point the rod at the fish and haul, until I feel it turn and as soon as that power comes through I slip line and lift the rod to cushion the dive. A #10 will exert more sustained pressure than a lighter rod weight. On the kayak, the limit of pressure, unless on a drogue, anchor or straight over the fish, is the glide of the kayak - you pull the kayak through the water. the same with a boat, but it takes more to get a heavy boat moving.
My own pike trace is made up from 30lb fluorocarbon ending in 56lb single strand wire. I am giving that Authanic a go to see how it fares.
Putting pressure on fish is not just the rod, but it does help if you want some shock absorption - plus the flex of the rod helps to keep the line taught, as it can spring straighter to keep pressure on the line MUCH faster than I can haul or wind.
Bigger weight rods are used to cast a heavier line, true, and the heavier line will carry a bigger or heavier fly, also true. However, I don't of anyone who uses a big fly to catch small fish, so the bigger rod is, by default, used to catch bigger fish. So, the #10 is the PREFERRED weight for pike.