The alpha slot and the accolade work completely differently.
The Alpha Slot slotted with the 33% Endurance Reduction will act like an additional Endurance Reduction SO in each power that can accept said enhancements. (Then factor in ED, etc to get your actual percentage boost.)
The Accolade increases the amount of endurance in your blue bar from 100 to 105.
They do not interfere with each other at all, and so you'll get the full effect from both of them.
...I forgot what experience means.
That said, they do work together very well.
Marshal increases your endurance by 5, which also increases your recovery (as recovery is a percentage of your total endurance for each tick)
Endurance Reduction reduces the amount of endurance each of your attacks use.
If you had, say, +49.8% recovery from Stamina, and +10% recovery from inventions, you'd have an average recovery of 1.67 x 1.598 = 2.67 endurance per second.
With the Marshal accolade, that gets increased by 5%, to 2.80 endurance per second.
Supposing your attack chain and toggles have 33.3% endurance reduction before adding the Alpha slot, and go through 5.00 endurance per second, you'd have a net loss of 2.20 endurance per second, and run out of endurance in 47.7 seconds (which is pretty normal...perhaps even long for "only" 5.00 endurance per second being spent at 33.3% endurance reduction)
Adding the Alpha slot enhancement to that would increase your endurance reduction to 66.3%, which would change your endurance consumption using the same sequence from 5.00 endurance per second to 4.01 endurance per second, changing your net loss of endurance to 1.19 endurance per second. Congratulations, you can now go "all out" for 88.2 seconds!
If you could increase your recovery and/or decrease your endurance consumption to the point where you can go "all out" and not use endurance in excess of your recovery, then you've reached the point of perpetual motion, where you're free to unleash your attacks without need for pause (unless, of course, something smacks you with a fair amount of endurance drain and/or a recovery penalty)
If I Alpha slot endurance and my Endurance is boosted 33 percent does that stack with the marshal accolade?