Xenon bulb

There are lights mounted on the seat wall that goes around my paver patio. I need to replace some of them. The bulbs are either 10W or 5W T3.5 Xenon wedge base LED lamps. I'm having trouble finding replacements. The closest I can find are at Lowes, but the lowest wattage is 18W. I think that might be too much. Also, what does the T3.5 mean? Is Xenon a brand name or a type of bulb?
Any help in finding the correct replacements will be appreciated.