Strike seems to give 1 experience point per damage it does. It may do less damage because you already did some or because there isn't that much health left. Strike damage didn't seem to change with my level at all. It only changed with the wave level, to always do half the heart's health.
that's interesting, low lvl players seem to do about 1/4 dmg but then again they dont have strike they have sear. So we may all be capped at the 50% but they cant do theirs in one Strike. I seem to get slightly different amounts of xp for every Strike, it was around a thousand, though sometimes 600'ish. Though that was before today's update which I havent seen posted but we can see in game the kill and assist now do half the xp they did yesterday lol
I think the killing blow xp is misplaced and should go to top dmg. No sense incentivizing ppl to try to get the last blow. The dmg is already broke into cycles,, may as well make the xp distribute properly to those that contributed dmg in that cycle.
I noticed you have way more Energy than I do as well. In another comment you were mid 20's lvl and said you had 130, gaining about 10 a day.
I got 10 at lvl 12 to make 110 and then stayed there until around lvl 35/40 and now have 120 (lvl 45).