Hi myself and another person are going to Italy and briefly to Lucerne Switzerland in September.
I see that even with a rail pass I would need to reserve a seat for most of the time. The cost of p2p vs rail pass is quite close for us. I am wanting to know that if I was to buy p2p tickets does this reserve me a seat? Because I think that if this is the case p2p would be cheaper. Our route is Rome-Florence-Venice-Lucerne-Rome.
If you buy certain P-P tickets (e.g., Italian EuroStar) at the counter in Italy, reservations are required and included. On other trains, such as IC, reservations are not required but are only a few Euro. The Trenitalia website should show the prices with and without optional reservations. If you buy tickets here in this country from a seller like RailEurope, reservations are probably mandatory and expensive.
You really don't need a railpass for Italy. What you are missing in your calcuations is that Italy charges a seat reservation fee of 15E-20E to Eurail passholders for riding on the Eurostars. And, the Eurostars on the runs you show above are mostly ES-Alta Velocitas these days. This is the 20E fee train. You can see all of this on the Eurail website. Add about 115CAD to the cost of your railpass if you want to ride the Eurostars in Italy.
P2P is almost always less expensive than a railpass in Italy. Plus, it's not as convenient as you may think if you ride the Eurostars. You still have to stand in line to get your seat reservation.
As Lee mentions above, whenever you purchase a P2P ticket in Italy, the seat reservation, if required, automatically comes with it. They are not separate with the P2P ticket.