How many times have I seen this? Too many!
Customer has fish on and having trouble getting fish over the rail. Mate grabs the rod half way up and swings fish. He just reduced the length of the blank in half and is putting all the stress on the top of the rod. This is fine if the mates does in on the boat rods as it becomes their problem if rod breaks. But then most pb rods are beasts or very flexible. DO NOT do that to any rod that I am using.
If a nice fish is coming up ask for the net OR wind up, get the fish on the surface, lean over the rail and lift the fish in holding the leader.
Yes, I agree swinging fish is a ton of fun, especially big blues. But you need a lot pof room to swing them properly. You need room behind you so that the lift is in one easy motion. Once you have the fish flying it's momentum will do the rest so the tip is not doing the work. Then let the tip follow the direction of the fish. As it hits the deck, release line so the tip is free.
Think about this. Every blank is rated for a casting range, say 1-3 ounces. That is the range of lures that the tip can handle when casting. Now when that same blank is used to swing big fish the top area of the rod is over loaded.
I suspect you swung that fish pretty fast. If you had been slower I think the blank would be in 2 or 3 pieces as the graphite material would have been twisted and shredded due to the stress.
Folks these blanks we are using today can not take the abuse the blanks of 30 years ago could. It is a new ball game. Most of the blanks I build on I tell my customers that they are finesse sticks and treat them as such. We have 30# class blanks with #7 tips. Years ago that would be a #12 or better. We are fishing with blanks that weight less than 2 ounces instead of 6 or 7 ounces. Yes, graphite is more sensitive and stronger but that comes with a price. They have to be treated kindly!
If a blank fails during the first couple of usages a good guess is that it was a manufacturing defect. I have had a blank break the first time I checked the spine before building it. That is mo where near the pressure a fish would put on it.
I do find that the blank manufacturers are very good when replacing blanks/rods. I would call them again. Maybe some one had a bad day or the person before your call/inspection gave the employee a hard time. Good fortune.
I hope this helps.