The repair system has changed. It used to be 10 levels minimum, i.e. to repair armor lvl 38, bronze plate, you had to be level 28 armorer at least (With or w/o guild support, which does nothing as for repairing I think). I repaired bronze plate armor (cuirass, sabatons, etc) at 24 armorer, making it at least a 14 level minimum now.
I was level armorer soley to repair my gear (same with BSM) now, it seems I don't have to go as high a level.
Needs further testing to find the REAL minimum, thanks. I'm thinking 20 levels.
My own theory
LW R19-20 can repair Bronze Plate Belt (R38) but can not attempt Leather Skirt (R37) or Tarred Leather Thighboots (R36). My theory is that the new repair system is:
Optimal Rank (OR) for Recipe (synth) is compared to Optimal Rank for Item.
If OR for Recipe < OR for Item, OR for Recipe is used. Following previous pattern of OR -10 ranks for NQ and +5 ranks for every HQ +
If OR for Recipe > OR for Item, OR for Item is used. Following the previous pattern of OR -10 ranks for NQ and +5 ranks for every HQ +
For example, Bronze Plate Belt OR for Recipe is around R20 but OR for Item is R38. OR for Recipe is used, hence the lowest Rank to repair NQ is 18.
Tarred Leather Thighboots and Leather Skirt OR for Recipe is R35+ and OR for Item is R36/37, hence the lowest Rank to repair NQ is 25+
I could repair Silver Magnifier Green (R36) at R37 before I can actually attempt it at R38+ Goldsmith -> The OR for Recipe is roughly first level to attempt + 10 -> 48, hence the Item OR was used.
This is to ensure that you can fix all the R50 +3 items, because all those Synths Optimal Rank are not 50, but closer to 45, so you only need R50 Craft to repair them and not R55.
FYI I have zero ARM rank but I can still repair the Bronze Plate Belt.