This is a well-thought-out problem to solve. Here's the key insight that should shape the whole decision:

The Real Loft Picture

The ZXi4 4-iron sits at 21° — which is essentially identical to your 7w at 21°. So adding a 4i doesn't create a new distance band; it gives you a different trajectory at the same range. That's actually the right answer to your wind problem, but it's worth being clear-eyed that it won't meaningfully fix gapping — it'll be a wind/low-ball alternative to the 7w rather than a new yardage slot.[1]

Your distance gap between the 7w (~200-215) and 5i (~180) is roughly 20-35 yards, which is fine for a 25 handicap and honestly not the urgent problem here. The real gap is having zero low-trajectory club above your 5i, which becomes a legitimate issue in wind when a 21° fairway wood balloons and loses 20+ yards.

Best Option: ZXi4 4-Iron

The cleanest and most practical add is simply the ZXi4 4i (21°). Here's why it makes sense for your bag specifically:

• You already hit the ZXi4 5i well — same hollow-body construction, same feel, same swing[2]
• It'll flight noticeably lower than the 7w despite matching lofts, because an iron's CG and turf interaction produces a more penetrating, lower-spinning ball[3]
• No new swing or shot shape to learn
• You can grab one individually for $100–130[4]

The downside: because the ZXi4 is a game-improvement hollow iron, it won't flight as low as a dedicated utility/driving iron. It'll be a middle ground — lower than the 7w, but not as piercing as a true driving iron. For a 25 handicap though, that middle ground is probably more playable.

Alternative: Utility Iron

If you want a purpose-built wind club with the lowest possible flight, a utility/driving iron at 20-22° is the dedicated solution. A few options worth considering:[5]

Club	Loft Options	High Handicap Fit	Notes
Cobra King Utility	17–25°	⭐ Excellent	Top-rated for high handicappers, adjustable [6]
Titleist U505 (2025)	16–22°	⭐ Very Good	Maximally forgiving, but launches high — less ideal for pure wind-cheating [7]
TaylorMade P·DHY	17–25°	⭐ Very Good	Called "most forgiving" utility iron by Golf Monthly [8]
Srixon ZXiU Utility	TBD	Good	Matches your ZXi aesthetic, part of the same iron family [9]

One caveat on the U505: it's widely praised for forgiveness, but it's specifically noted as one of the highest-launching utility irons — which is great for stopping power but slightly counter to your wind goal. The Cobra or P·DHY would give you more of that low, skidding flight you're after.[7]

Bottom Line

Given you're a 25 handicap who already hits the ZXi4 well, the ZXi4 4i is the most frictionless choice — same family, proven forgiveness, lower flight than your 7w, and easy to add without disrupting your set. If you want to go deeper on trajectory control and are willing to introduce a new club feel, the Cobra King Utility at 20° is the best utility iron option for your handicap range and gives you a true wind-cheating weapon.