To alleviate the pressure and discomfort on your arches you can use these.
1st of all they do not fit alloy climbers, my climbers are steel Bashlin's.
They sort of clip together and there's two screws with shake proof washers that hold them together.
Here's a link to their website, they're about half way down.
Buckingham Mfg. Climber Pads, straps and plates for hooks, leg irons or pole spikes
You can have short or long gaffs, up to you, in these pics I have long gaffs fitted to the climbers.
You need to make sure that the boots you are wearing have sufficient arch clearance for them though. If your boots are too flat then the whole exercise is futile. When I buy boots I take these with me.
I do a lot of palms and they're good for that, however in a tree I tend to climb on Bashlin alloys without (and they dont fit) foot plates. That's because you get better underfoot feeling for branches and can stand in crotches.
The foot plates can jump out of the boots arch area from time to time, that's a real PITA, usually means loosening off a strap and repostioning it then tightening up the climber strap again. Again, more likely to happen from crotches in trees.
There is another product out too called Talon climbers. I cannot comment on those but do believe there's the odd member and lurkers who do own them, hopefully they pipe up.
Fresco Arborist Supplies
More pics attached, check them out.