*This page has become my tried and tested favorite for Season 4, it has worked for me and I hope it works for you as well. Remember that all of these Mastery Pages can be mixed and matched to fit your personal preference and style!
With Double-Edged Sword, you receive more damage, however your own damage is increased as well. A very straight forward mastery; it is well worth the trade for Jayce's damage output. (Tip: % Damage/recieved adjusts between melee and ranged stance.
Bringing two points into this will aid you in auto attacking people to death early levels, use it to your advantage!
Butcher is a really nice mastery to have, it helps you a lot while trying to CS. Remember that 20 CS is roughly the same amount of gold as 1 kill. So DON'T MISS YOUR LAST HITS!
Feast provides free sustain, giving you up to 12 Health and 6 Mana if you kill all 6 minions every 30 seconds. (7 minions every 3rd wave.
Brute Force gives you more Attack Damage per level, increasing your overall damage throughout the game.
Jayce often harasses with auto attacks in lane. Get a point in Spell Weaving so your upcoming spells do more damage. (Tip: Procs with Jayce's three Hyper Charge auto attacks.
Martial Mastery is basically 2 free AD Quints. Getting this allows for easier CS, more harass, and damage in the laning phase.
Executioner increases your damage on champions below 50% Health by 5%. Max this mastery for better kill potential on enemies.
Blade Weaving works well with Jayce because he auto attacks often between spells.
5% increase in Attack damage is good for any AD oriented damage dealer.
DANGEROUS GAME (Mastery pictures turned into S3 Masteries in Editor...) - This has become one of my favorite masteries, it can literally mean life or death. If you ever find yourself dieing to that last tick of ignite or last turret hit after diving someone, this may be your answer to living through that.
Devastating Strike gives 6% Armor and Magic Penetration at 3/3 points. You CAN max this, but I prefer only bringing 2/3 to leave points open for more parts of the Offense tree.
Havoc gives 3% increased damage which works alongside Executioner and Double-Edged Sword. Having these three masteries together increases your damage by 9.5% in Cannon Stance and 10% in Hammer Stance. Putting a point in this allows you to maximize your damage potential.
Taking 2/2 points into Block helps you sustain against ranged opponents in lane by weakening their harass.
Recovery allows you to sustain Health in lane much more efficiently.
Putting a point in Unyielding just lowers the overall damage you take from Champions. While it may not seem like a lot, this could be the determining factor of who wins or loses during a trade. (Tip: Does not work against true damage.
I like having at least 1 point in this, free health is always a good thing.
You can work this together with Tear of the Goddess giving Jayce +9 Mana Regen, letting you to spam your abilities throughout the game. This is also important to bring if you aren't building Tear as well, helping sustain your mana problems.